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diff --git a/test/monniaux/glpk-4.65/src/amd/amd_2.c b/test/monniaux/glpk-4.65/src/amd/amd_2.c new file mode 100644 index 00000000..36ae828a --- /dev/null +++ b/test/monniaux/glpk-4.65/src/amd/amd_2.c @@ -0,0 +1,1842 @@ +/* ========================================================================= */ +/* === AMD_2 =============================================================== */ +/* ========================================================================= */ + +/* ------------------------------------------------------------------------- */ +/* AMD, Copyright (c) Timothy A. Davis, */ +/* Patrick R. Amestoy, and Iain S. Duff. See ../README.txt for License. */ +/* email: davis at cise.ufl.edu CISE Department, Univ. of Florida. */ +/* web: http://www.cise.ufl.edu/research/sparse/amd */ +/* ------------------------------------------------------------------------- */ + +/* AMD_2: performs the AMD ordering on a symmetric sparse matrix A, followed + * by a postordering (via depth-first search) of the assembly tree using the + * AMD_postorder routine. + */ + +#include "amd_internal.h" + +/* ========================================================================= */ +/* === clear_flag ========================================================== */ +/* ========================================================================= */ + +static Int clear_flag (Int wflg, Int wbig, Int W [ ], Int n) +{ + Int x ; + if (wflg < 2 || wflg >= wbig) + { + for (x = 0 ; x < n ; x++) + { + if (W [x] != 0) W [x] = 1 ; + } + wflg = 2 ; + } + /* at this point, W [0..n-1] < wflg holds */ + return (wflg) ; +} + + +/* ========================================================================= */ +/* === AMD_2 =============================================================== */ +/* ========================================================================= */ + +GLOBAL void AMD_2 +( + Int n, /* A is n-by-n, where n > 0 */ + Int Pe [ ], /* Pe [0..n-1]: index in Iw of row i on input */ + Int Iw [ ], /* workspace of size iwlen. Iw [0..pfree-1] + * holds the matrix on input */ + Int Len [ ], /* Len [0..n-1]: length for row/column i on input */ + Int iwlen, /* length of Iw. iwlen >= pfree + n */ + Int pfree, /* Iw [pfree ... iwlen-1] is empty on input */ + + /* 7 size-n workspaces, not defined on input: */ + Int Nv [ ], /* the size of each supernode on output */ + Int Next [ ], /* the output inverse permutation */ + Int Last [ ], /* the output permutation */ + Int Head [ ], + Int Elen [ ], /* the size columns of L for each supernode */ + Int Degree [ ], + Int W [ ], + + /* control parameters and output statistics */ + double Control [ ], /* array of size AMD_CONTROL */ + double Info [ ] /* array of size AMD_INFO */ +) +{ + +/* + * Given a representation of the nonzero pattern of a symmetric matrix, A, + * (excluding the diagonal) perform an approximate minimum (UMFPACK/MA38-style) + * degree ordering to compute a pivot order such that the introduction of + * nonzeros (fill-in) in the Cholesky factors A = LL' is kept low. At each + * step, the pivot selected is the one with the minimum UMFAPACK/MA38-style + * upper-bound on the external degree. This routine can optionally perform + * aggresive absorption (as done by MC47B in the Harwell Subroutine + * Library). + * + * The approximate degree algorithm implemented here is the symmetric analog of + * the degree update algorithm in MA38 and UMFPACK (the Unsymmetric-pattern + * MultiFrontal PACKage, both by Davis and Duff). The routine is based on the + * MA27 minimum degree ordering algorithm by Iain Duff and John Reid. + * + * This routine is a translation of the original AMDBAR and MC47B routines, + * in Fortran, with the following modifications: + * + * (1) dense rows/columns are removed prior to ordering the matrix, and placed + * last in the output order. The presence of a dense row/column can + * increase the ordering time by up to O(n^2), unless they are removed + * prior to ordering. + * + * (2) the minimum degree ordering is followed by a postordering (depth-first + * search) of the assembly tree. Note that mass elimination (discussed + * below) combined with the approximate degree update can lead to the mass + * elimination of nodes with lower exact degree than the current pivot + * element. No additional fill-in is caused in the representation of the + * Schur complement. The mass-eliminated nodes merge with the current + * pivot element. They are ordered prior to the current pivot element. + * Because they can have lower exact degree than the current element, the + * merger of two or more of these nodes in the current pivot element can + * lead to a single element that is not a "fundamental supernode". The + * diagonal block can have zeros in it. Thus, the assembly tree used here + * is not guaranteed to be the precise supernodal elemination tree (with + * "funadmental" supernodes), and the postordering performed by this + * routine is not guaranteed to be a precise postordering of the + * elimination tree. + * + * (3) input parameters are added, to control aggressive absorption and the + * detection of "dense" rows/columns of A. + * + * (4) additional statistical information is returned, such as the number of + * nonzeros in L, and the flop counts for subsequent LDL' and LU + * factorizations. These are slight upper bounds, because of the mass + * elimination issue discussed above. + * + * (5) additional routines are added to interface this routine to MATLAB + * to provide a simple C-callable user-interface, to check inputs for + * errors, compute the symmetry of the pattern of A and the number of + * nonzeros in each row/column of A+A', to compute the pattern of A+A', + * to perform the assembly tree postordering, and to provide debugging + * ouput. Many of these functions are also provided by the Fortran + * Harwell Subroutine Library routine MC47A. + * + * (6) both int and UF_long versions are provided. In the descriptions below + * and integer is and int or UF_long depending on which version is + * being used. + + ********************************************************************** + ***** CAUTION: ARGUMENTS ARE NOT CHECKED FOR ERRORS ON INPUT. ****** + ********************************************************************** + ** If you want error checking, a more versatile input format, and a ** + ** simpler user interface, use amd_order or amd_l_order instead. ** + ** This routine is not meant to be user-callable. ** + ********************************************************************** + + * ---------------------------------------------------------------------------- + * References: + * ---------------------------------------------------------------------------- + * + * [1] Timothy A. Davis and Iain Duff, "An unsymmetric-pattern multifrontal + * method for sparse LU factorization", SIAM J. Matrix Analysis and + * Applications, vol. 18, no. 1, pp. 140-158. Discusses UMFPACK / MA38, + * which first introduced the approximate minimum degree used by this + * routine. + * + * [2] Patrick Amestoy, Timothy A. Davis, and Iain S. Duff, "An approximate + * minimum degree ordering algorithm," SIAM J. Matrix Analysis and + * Applications, vol. 17, no. 4, pp. 886-905, 1996. Discusses AMDBAR and + * MC47B, which are the Fortran versions of this routine. + * + * [3] Alan George and Joseph Liu, "The evolution of the minimum degree + * ordering algorithm," SIAM Review, vol. 31, no. 1, pp. 1-19, 1989. + * We list below the features mentioned in that paper that this code + * includes: + * + * mass elimination: + * Yes. MA27 relied on supervariable detection for mass elimination. + * + * indistinguishable nodes: + * Yes (we call these "supervariables"). This was also in the MA27 + * code - although we modified the method of detecting them (the + * previous hash was the true degree, which we no longer keep track + * of). A supervariable is a set of rows with identical nonzero + * pattern. All variables in a supervariable are eliminated together. + * Each supervariable has as its numerical name that of one of its + * variables (its principal variable). + * + * quotient graph representation: + * Yes. We use the term "element" for the cliques formed during + * elimination. This was also in the MA27 code. The algorithm can + * operate in place, but it will work more efficiently if given some + * "elbow room." + * + * element absorption: + * Yes. This was also in the MA27 code. + * + * external degree: + * Yes. The MA27 code was based on the true degree. + * + * incomplete degree update and multiple elimination: + * No. This was not in MA27, either. Our method of degree update + * within MC47B is element-based, not variable-based. It is thus + * not well-suited for use with incomplete degree update or multiple + * elimination. + * + * Authors, and Copyright (C) 2004 by: + * Timothy A. Davis, Patrick Amestoy, Iain S. Duff, John K. Reid. + * + * Acknowledgements: This work (and the UMFPACK package) was supported by the + * National Science Foundation (ASC-9111263, DMS-9223088, and CCR-0203270). + * The UMFPACK/MA38 approximate degree update algorithm, the unsymmetric analog + * which forms the basis of AMD, was developed while Tim Davis was supported by + * CERFACS (Toulouse, France) in a post-doctoral position. This C version, and + * the etree postorder, were written while Tim Davis was on sabbatical at + * Stanford University and Lawrence Berkeley National Laboratory. + + * ---------------------------------------------------------------------------- + * INPUT ARGUMENTS (unaltered): + * ---------------------------------------------------------------------------- + + * n: The matrix order. Restriction: n >= 1. + * + * iwlen: The size of the Iw array. On input, the matrix is stored in + * Iw [0..pfree-1]. However, Iw [0..iwlen-1] should be slightly larger + * than what is required to hold the matrix, at least iwlen >= pfree + n. + * Otherwise, excessive compressions will take place. The recommended + * value of iwlen is 1.2 * pfree + n, which is the value used in the + * user-callable interface to this routine (amd_order.c). The algorithm + * will not run at all if iwlen < pfree. Restriction: iwlen >= pfree + n. + * Note that this is slightly more restrictive than the actual minimum + * (iwlen >= pfree), but AMD_2 will be very slow with no elbow room. + * Thus, this routine enforces a bare minimum elbow room of size n. + * + * pfree: On input the tail end of the array, Iw [pfree..iwlen-1], is empty, + * and the matrix is stored in Iw [0..pfree-1]. During execution, + * additional data is placed in Iw, and pfree is modified so that + * Iw [pfree..iwlen-1] is always the unused part of Iw. + * + * Control: A double array of size AMD_CONTROL containing input parameters + * that affect how the ordering is computed. If NULL, then default + * settings are used. + * + * Control [AMD_DENSE] is used to determine whether or not a given input + * row is "dense". A row is "dense" if the number of entries in the row + * exceeds Control [AMD_DENSE] times sqrt (n), except that rows with 16 or + * fewer entries are never considered "dense". To turn off the detection + * of dense rows, set Control [AMD_DENSE] to a negative number, or to a + * number larger than sqrt (n). The default value of Control [AMD_DENSE] + * is AMD_DEFAULT_DENSE, which is defined in amd.h as 10. + * + * Control [AMD_AGGRESSIVE] is used to determine whether or not aggressive + * absorption is to be performed. If nonzero, then aggressive absorption + * is performed (this is the default). + + * ---------------------------------------------------------------------------- + * INPUT/OUPUT ARGUMENTS: + * ---------------------------------------------------------------------------- + * + * Pe: An integer array of size n. On input, Pe [i] is the index in Iw of + * the start of row i. Pe [i] is ignored if row i has no off-diagonal + * entries. Thus Pe [i] must be in the range 0 to pfree-1 for non-empty + * rows. + * + * During execution, it is used for both supervariables and elements: + * + * Principal supervariable i: index into Iw of the description of + * supervariable i. A supervariable represents one or more rows of + * the matrix with identical nonzero pattern. In this case, + * Pe [i] >= 0. + * + * Non-principal supervariable i: if i has been absorbed into another + * supervariable j, then Pe [i] = FLIP (j), where FLIP (j) is defined + * as (-(j)-2). Row j has the same pattern as row i. Note that j + * might later be absorbed into another supervariable j2, in which + * case Pe [i] is still FLIP (j), and Pe [j] = FLIP (j2) which is + * < EMPTY, where EMPTY is defined as (-1) in amd_internal.h. + * + * Unabsorbed element e: the index into Iw of the description of element + * e, if e has not yet been absorbed by a subsequent element. Element + * e is created when the supervariable of the same name is selected as + * the pivot. In this case, Pe [i] >= 0. + * + * Absorbed element e: if element e is absorbed into element e2, then + * Pe [e] = FLIP (e2). This occurs when the pattern of e (which we + * refer to as Le) is found to be a subset of the pattern of e2 (that + * is, Le2). In this case, Pe [i] < EMPTY. If element e is "null" + * (it has no nonzeros outside its pivot block), then Pe [e] = EMPTY, + * and e is the root of an assembly subtree (or the whole tree if + * there is just one such root). + * + * Dense variable i: if i is "dense", then Pe [i] = EMPTY. + * + * On output, Pe holds the assembly tree/forest, which implicitly + * represents a pivot order with identical fill-in as the actual order + * (via a depth-first search of the tree), as follows. If Nv [i] > 0, + * then i represents a node in the assembly tree, and the parent of i is + * Pe [i], or EMPTY if i is a root. If Nv [i] = 0, then (i, Pe [i]) + * represents an edge in a subtree, the root of which is a node in the + * assembly tree. Note that i refers to a row/column in the original + * matrix, not the permuted matrix. + * + * Info: A double array of size AMD_INFO. If present, (that is, not NULL), + * then statistics about the ordering are returned in the Info array. + * See amd.h for a description. + + * ---------------------------------------------------------------------------- + * INPUT/MODIFIED (undefined on output): + * ---------------------------------------------------------------------------- + * + * Len: An integer array of size n. On input, Len [i] holds the number of + * entries in row i of the matrix, excluding the diagonal. The contents + * of Len are undefined on output. + * + * Iw: An integer array of size iwlen. On input, Iw [0..pfree-1] holds the + * description of each row i in the matrix. The matrix must be symmetric, + * and both upper and lower triangular parts must be present. The + * diagonal must not be present. Row i is held as follows: + * + * Len [i]: the length of the row i data structure in the Iw array. + * Iw [Pe [i] ... Pe [i] + Len [i] - 1]: + * the list of column indices for nonzeros in row i (simple + * supervariables), excluding the diagonal. All supervariables + * start with one row/column each (supervariable i is just row i). + * If Len [i] is zero on input, then Pe [i] is ignored on input. + * + * Note that the rows need not be in any particular order, and there + * may be empty space between the rows. + * + * During execution, the supervariable i experiences fill-in. This is + * represented by placing in i a list of the elements that cause fill-in + * in supervariable i: + * + * Len [i]: the length of supervariable i in the Iw array. + * Iw [Pe [i] ... Pe [i] + Elen [i] - 1]: + * the list of elements that contain i. This list is kept short + * by removing absorbed elements. + * Iw [Pe [i] + Elen [i] ... Pe [i] + Len [i] - 1]: + * the list of supervariables in i. This list is kept short by + * removing nonprincipal variables, and any entry j that is also + * contained in at least one of the elements (j in Le) in the list + * for i (e in row i). + * + * When supervariable i is selected as pivot, we create an element e of + * the same name (e=i): + * + * Len [e]: the length of element e in the Iw array. + * Iw [Pe [e] ... Pe [e] + Len [e] - 1]: + * the list of supervariables in element e. + * + * An element represents the fill-in that occurs when supervariable i is + * selected as pivot (which represents the selection of row i and all + * non-principal variables whose principal variable is i). We use the + * term Le to denote the set of all supervariables in element e. Absorbed + * supervariables and elements are pruned from these lists when + * computationally convenient. + * + * CAUTION: THE INPUT MATRIX IS OVERWRITTEN DURING COMPUTATION. + * The contents of Iw are undefined on output. + + * ---------------------------------------------------------------------------- + * OUTPUT (need not be set on input): + * ---------------------------------------------------------------------------- + * + * Nv: An integer array of size n. During execution, ABS (Nv [i]) is equal to + * the number of rows that are represented by the principal supervariable + * i. If i is a nonprincipal or dense variable, then Nv [i] = 0. + * Initially, Nv [i] = 1 for all i. Nv [i] < 0 signifies that i is a + * principal variable in the pattern Lme of the current pivot element me. + * After element me is constructed, Nv [i] is set back to a positive + * value. + * + * On output, Nv [i] holds the number of pivots represented by super + * row/column i of the original matrix, or Nv [i] = 0 for non-principal + * rows/columns. Note that i refers to a row/column in the original + * matrix, not the permuted matrix. + * + * Elen: An integer array of size n. See the description of Iw above. At the + * start of execution, Elen [i] is set to zero for all rows i. During + * execution, Elen [i] is the number of elements in the list for + * supervariable i. When e becomes an element, Elen [e] = FLIP (esize) is + * set, where esize is the size of the element (the number of pivots, plus + * the number of nonpivotal entries). Thus Elen [e] < EMPTY. + * Elen (i) = EMPTY set when variable i becomes nonprincipal. + * + * For variables, Elen (i) >= EMPTY holds until just before the + * postordering and permutation vectors are computed. For elements, + * Elen [e] < EMPTY holds. + * + * On output, Elen [i] is the degree of the row/column in the Cholesky + * factorization of the permuted matrix, corresponding to the original row + * i, if i is a super row/column. It is equal to EMPTY if i is + * non-principal. Note that i refers to a row/column in the original + * matrix, not the permuted matrix. + * + * Note that the contents of Elen on output differ from the Fortran + * version (Elen holds the inverse permutation in the Fortran version, + * which is instead returned in the Next array in this C version, + * described below). + * + * Last: In a degree list, Last [i] is the supervariable preceding i, or EMPTY + * if i is the head of the list. In a hash bucket, Last [i] is the hash + * key for i. + * + * Last [Head [hash]] is also used as the head of a hash bucket if + * Head [hash] contains a degree list (see the description of Head, + * below). + * + * On output, Last [0..n-1] holds the permutation. That is, if + * i = Last [k], then row i is the kth pivot row (where k ranges from 0 to + * n-1). Row Last [k] of A is the kth row in the permuted matrix, PAP'. + * + * Next: Next [i] is the supervariable following i in a link list, or EMPTY if + * i is the last in the list. Used for two kinds of lists: degree lists + * and hash buckets (a supervariable can be in only one kind of list at a + * time). + * + * On output Next [0..n-1] holds the inverse permutation. That is, if + * k = Next [i], then row i is the kth pivot row. Row i of A appears as + * the (Next[i])-th row in the permuted matrix, PAP'. + * + * Note that the contents of Next on output differ from the Fortran + * version (Next is undefined on output in the Fortran version). + + * ---------------------------------------------------------------------------- + * LOCAL WORKSPACE (not input or output - used only during execution): + * ---------------------------------------------------------------------------- + * + * Degree: An integer array of size n. If i is a supervariable, then + * Degree [i] holds the current approximation of the external degree of + * row i (an upper bound). The external degree is the number of nonzeros + * in row i, minus ABS (Nv [i]), the diagonal part. The bound is equal to + * the exact external degree if Elen [i] is less than or equal to two. + * + * We also use the term "external degree" for elements e to refer to + * |Le \ Lme|. If e is an element, then Degree [e] is |Le|, which is the + * degree of the off-diagonal part of the element e (not including the + * diagonal part). + * + * Head: An integer array of size n. Head is used for degree lists. + * Head [deg] is the first supervariable in a degree list. All + * supervariables i in a degree list Head [deg] have the same approximate + * degree, namely, deg = Degree [i]. If the list Head [deg] is empty then + * Head [deg] = EMPTY. + * + * During supervariable detection Head [hash] also serves as a pointer to + * a hash bucket. If Head [hash] >= 0, there is a degree list of degree + * hash. The hash bucket head pointer is Last [Head [hash]]. If + * Head [hash] = EMPTY, then the degree list and hash bucket are both + * empty. If Head [hash] < EMPTY, then the degree list is empty, and + * FLIP (Head [hash]) is the head of the hash bucket. After supervariable + * detection is complete, all hash buckets are empty, and the + * (Last [Head [hash]] = EMPTY) condition is restored for the non-empty + * degree lists. + * + * W: An integer array of size n. The flag array W determines the status of + * elements and variables, and the external degree of elements. + * + * for elements: + * if W [e] = 0, then the element e is absorbed. + * if W [e] >= wflg, then W [e] - wflg is the size of the set + * |Le \ Lme|, in terms of nonzeros (the sum of ABS (Nv [i]) for + * each principal variable i that is both in the pattern of + * element e and NOT in the pattern of the current pivot element, + * me). + * if wflg > W [e] > 0, then e is not absorbed and has not yet been + * seen in the scan of the element lists in the computation of + * |Le\Lme| in Scan 1 below. + * + * for variables: + * during supervariable detection, if W [j] != wflg then j is + * not in the pattern of variable i. + * + * The W array is initialized by setting W [i] = 1 for all i, and by + * setting wflg = 2. It is reinitialized if wflg becomes too large (to + * ensure that wflg+n does not cause integer overflow). + + * ---------------------------------------------------------------------------- + * LOCAL INTEGERS: + * ---------------------------------------------------------------------------- + */ + + Int deg, degme, dext, lemax, e, elenme, eln, i, ilast, inext, j, + jlast, jnext, k, knt1, knt2, knt3, lenj, ln, me, mindeg, nel, nleft, + nvi, nvj, nvpiv, slenme, wbig, we, wflg, wnvi, ok, ndense, ncmpa, + dense, aggressive ; + + unsigned Int hash ; /* unsigned, so that hash % n is well defined.*/ + +/* + * deg: the degree of a variable or element + * degme: size, |Lme|, of the current element, me (= Degree [me]) + * dext: external degree, |Le \ Lme|, of some element e + * lemax: largest |Le| seen so far (called dmax in Fortran version) + * e: an element + * elenme: the length, Elen [me], of element list of pivotal variable + * eln: the length, Elen [...], of an element list + * hash: the computed value of the hash function + * i: a supervariable + * ilast: the entry in a link list preceding i + * inext: the entry in a link list following i + * j: a supervariable + * jlast: the entry in a link list preceding j + * jnext: the entry in a link list, or path, following j + * k: the pivot order of an element or variable + * knt1: loop counter used during element construction + * knt2: loop counter used during element construction + * knt3: loop counter used during compression + * lenj: Len [j] + * ln: length of a supervariable list + * me: current supervariable being eliminated, and the current + * element created by eliminating that supervariable + * mindeg: current minimum degree + * nel: number of pivots selected so far + * nleft: n - nel, the number of nonpivotal rows/columns remaining + * nvi: the number of variables in a supervariable i (= Nv [i]) + * nvj: the number of variables in a supervariable j (= Nv [j]) + * nvpiv: number of pivots in current element + * slenme: number of variables in variable list of pivotal variable + * wbig: = INT_MAX - n for the int version, UF_long_max - n for the + * UF_long version. wflg is not allowed to be >= wbig. + * we: W [e] + * wflg: used for flagging the W array. See description of Iw. + * wnvi: wflg - Nv [i] + * x: either a supervariable or an element + * + * ok: true if supervariable j can be absorbed into i + * ndense: number of "dense" rows/columns + * dense: rows/columns with initial degree > dense are considered "dense" + * aggressive: true if aggressive absorption is being performed + * ncmpa: number of garbage collections + + * ---------------------------------------------------------------------------- + * LOCAL DOUBLES, used for statistical output only (except for alpha): + * ---------------------------------------------------------------------------- + */ + + double f, r, ndiv, s, nms_lu, nms_ldl, dmax, alpha, lnz, lnzme ; + +/* + * f: nvpiv + * r: degme + nvpiv + * ndiv: number of divisions for LU or LDL' factorizations + * s: number of multiply-subtract pairs for LU factorization, for the + * current element me + * nms_lu number of multiply-subtract pairs for LU factorization + * nms_ldl number of multiply-subtract pairs for LDL' factorization + * dmax: the largest number of entries in any column of L, including the + * diagonal + * alpha: "dense" degree ratio + * lnz: the number of nonzeros in L (excluding the diagonal) + * lnzme: the number of nonzeros in L (excl. the diagonal) for the + * current element me + + * ---------------------------------------------------------------------------- + * LOCAL "POINTERS" (indices into the Iw array) + * ---------------------------------------------------------------------------- +*/ + + Int p, p1, p2, p3, p4, pdst, pend, pj, pme, pme1, pme2, pn, psrc ; + +/* + * Any parameter (Pe [...] or pfree) or local variable starting with "p" (for + * Pointer) is an index into Iw, and all indices into Iw use variables starting + * with "p." The only exception to this rule is the iwlen input argument. + * + * p: pointer into lots of things + * p1: Pe [i] for some variable i (start of element list) + * p2: Pe [i] + Elen [i] - 1 for some variable i + * p3: index of first supervariable in clean list + * p4: + * pdst: destination pointer, for compression + * pend: end of memory to compress + * pj: pointer into an element or variable + * pme: pointer into the current element (pme1...pme2) + * pme1: the current element, me, is stored in Iw [pme1...pme2] + * pme2: the end of the current element + * pn: pointer into a "clean" variable, also used to compress + * psrc: source pointer, for compression +*/ + +/* ========================================================================= */ +/* INITIALIZATIONS */ +/* ========================================================================= */ + + /* Note that this restriction on iwlen is slightly more restrictive than + * what is actually required in AMD_2. AMD_2 can operate with no elbow + * room at all, but it will be slow. For better performance, at least + * size-n elbow room is enforced. */ + ASSERT (iwlen >= pfree + n) ; + ASSERT (n > 0) ; + + /* initialize output statistics */ + lnz = 0 ; + ndiv = 0 ; + nms_lu = 0 ; + nms_ldl = 0 ; + dmax = 1 ; + me = EMPTY ; + + mindeg = 0 ; + ncmpa = 0 ; + nel = 0 ; + lemax = 0 ; + + /* get control parameters */ + if (Control != (double *) NULL) + { + alpha = Control [AMD_DENSE] ; + aggressive = (Control [AMD_AGGRESSIVE] != 0) ; + } + else + { + alpha = AMD_DEFAULT_DENSE ; + aggressive = AMD_DEFAULT_AGGRESSIVE ; + } + /* Note: if alpha is NaN, this is undefined: */ + if (alpha < 0) + { + /* only remove completely dense rows/columns */ + dense = n-2 ; + } + else + { + dense = alpha * sqrt ((double) n) ; + } + dense = MAX (16, dense) ; + dense = MIN (n, dense) ; + AMD_DEBUG1 (("\n\nAMD (debug), alpha %g, aggr. "ID"\n", + alpha, aggressive)) ; + + for (i = 0 ; i < n ; i++) + { + Last [i] = EMPTY ; + Head [i] = EMPTY ; + Next [i] = EMPTY ; + /* if separate Hhead array is used for hash buckets: * + Hhead [i] = EMPTY ; + */ + Nv [i] = 1 ; + W [i] = 1 ; + Elen [i] = 0 ; + Degree [i] = Len [i] ; + } + +#ifndef NDEBUG + AMD_DEBUG1 (("\n======Nel "ID" initial\n", nel)) ; + AMD_dump (n, Pe, Iw, Len, iwlen, pfree, Nv, Next, Last, + Head, Elen, Degree, W, -1) ; +#endif + + /* initialize wflg */ + wbig = Int_MAX - n ; + wflg = clear_flag (0, wbig, W, n) ; + + /* --------------------------------------------------------------------- */ + /* initialize degree lists and eliminate dense and empty rows */ + /* --------------------------------------------------------------------- */ + + ndense = 0 ; + + for (i = 0 ; i < n ; i++) + { + deg = Degree [i] ; + ASSERT (deg >= 0 && deg < n) ; + if (deg == 0) + { + + /* ------------------------------------------------------------- + * we have a variable that can be eliminated at once because + * there is no off-diagonal non-zero in its row. Note that + * Nv [i] = 1 for an empty variable i. It is treated just + * the same as an eliminated element i. + * ------------------------------------------------------------- */ + + Elen [i] = FLIP (1) ; + nel++ ; + Pe [i] = EMPTY ; + W [i] = 0 ; + + } + else if (deg > dense) + { + + /* ------------------------------------------------------------- + * Dense variables are not treated as elements, but as unordered, + * non-principal variables that have no parent. They do not take + * part in the postorder, since Nv [i] = 0. Note that the Fortran + * version does not have this option. + * ------------------------------------------------------------- */ + + AMD_DEBUG1 (("Dense node "ID" degree "ID"\n", i, deg)) ; + ndense++ ; + Nv [i] = 0 ; /* do not postorder this node */ + Elen [i] = EMPTY ; + nel++ ; + Pe [i] = EMPTY ; + + } + else + { + + /* ------------------------------------------------------------- + * place i in the degree list corresponding to its degree + * ------------------------------------------------------------- */ + + inext = Head [deg] ; + ASSERT (inext >= EMPTY && inext < n) ; + if (inext != EMPTY) Last [inext] = i ; + Next [i] = inext ; + Head [deg] = i ; + + } + } + +/* ========================================================================= */ +/* WHILE (selecting pivots) DO */ +/* ========================================================================= */ + + while (nel < n) + { + +#ifndef NDEBUG + AMD_DEBUG1 (("\n======Nel "ID"\n", nel)) ; + if (AMD_debug >= 2) + { + AMD_dump (n, Pe, Iw, Len, iwlen, pfree, Nv, Next, + Last, Head, Elen, Degree, W, nel) ; + } +#endif + +/* ========================================================================= */ +/* GET PIVOT OF MINIMUM DEGREE */ +/* ========================================================================= */ + + /* ----------------------------------------------------------------- */ + /* find next supervariable for elimination */ + /* ----------------------------------------------------------------- */ + + ASSERT (mindeg >= 0 && mindeg < n) ; + for (deg = mindeg ; deg < n ; deg++) + { + me = Head [deg] ; + if (me != EMPTY) break ; + } + mindeg = deg ; + ASSERT (me >= 0 && me < n) ; + AMD_DEBUG1 (("=================me: "ID"\n", me)) ; + + /* ----------------------------------------------------------------- */ + /* remove chosen variable from link list */ + /* ----------------------------------------------------------------- */ + + inext = Next [me] ; + ASSERT (inext >= EMPTY && inext < n) ; + if (inext != EMPTY) Last [inext] = EMPTY ; + Head [deg] = inext ; + + /* ----------------------------------------------------------------- */ + /* me represents the elimination of pivots nel to nel+Nv[me]-1. */ + /* place me itself as the first in this set. */ + /* ----------------------------------------------------------------- */ + + elenme = Elen [me] ; + nvpiv = Nv [me] ; + ASSERT (nvpiv > 0) ; + nel += nvpiv ; + +/* ========================================================================= */ +/* CONSTRUCT NEW ELEMENT */ +/* ========================================================================= */ + + /* ----------------------------------------------------------------- + * At this point, me is the pivotal supervariable. It will be + * converted into the current element. Scan list of the pivotal + * supervariable, me, setting tree pointers and constructing new list + * of supervariables for the new element, me. p is a pointer to the + * current position in the old list. + * ----------------------------------------------------------------- */ + + /* flag the variable "me" as being in Lme by negating Nv [me] */ + Nv [me] = -nvpiv ; + degme = 0 ; + ASSERT (Pe [me] >= 0 && Pe [me] < iwlen) ; + + if (elenme == 0) + { + + /* ------------------------------------------------------------- */ + /* construct the new element in place */ + /* ------------------------------------------------------------- */ + + pme1 = Pe [me] ; + pme2 = pme1 - 1 ; + + for (p = pme1 ; p <= pme1 + Len [me] - 1 ; p++) + { + i = Iw [p] ; + ASSERT (i >= 0 && i < n && Nv [i] >= 0) ; + nvi = Nv [i] ; + if (nvi > 0) + { + + /* ----------------------------------------------------- */ + /* i is a principal variable not yet placed in Lme. */ + /* store i in new list */ + /* ----------------------------------------------------- */ + + /* flag i as being in Lme by negating Nv [i] */ + degme += nvi ; + Nv [i] = -nvi ; + Iw [++pme2] = i ; + + /* ----------------------------------------------------- */ + /* remove variable i from degree list. */ + /* ----------------------------------------------------- */ + + ilast = Last [i] ; + inext = Next [i] ; + ASSERT (ilast >= EMPTY && ilast < n) ; + ASSERT (inext >= EMPTY && inext < n) ; + if (inext != EMPTY) Last [inext] = ilast ; + if (ilast != EMPTY) + { + Next [ilast] = inext ; + } + else + { + /* i is at the head of the degree list */ + ASSERT (Degree [i] >= 0 && Degree [i] < n) ; + Head [Degree [i]] = inext ; + } + } + } + } + else + { + + /* ------------------------------------------------------------- */ + /* construct the new element in empty space, Iw [pfree ...] */ + /* ------------------------------------------------------------- */ + + p = Pe [me] ; + pme1 = pfree ; + slenme = Len [me] - elenme ; + + for (knt1 = 1 ; knt1 <= elenme + 1 ; knt1++) + { + + if (knt1 > elenme) + { + /* search the supervariables in me. */ + e = me ; + pj = p ; + ln = slenme ; + AMD_DEBUG2 (("Search sv: "ID" "ID" "ID"\n", me,pj,ln)) ; + } + else + { + /* search the elements in me. */ + e = Iw [p++] ; + ASSERT (e >= 0 && e < n) ; + pj = Pe [e] ; + ln = Len [e] ; + AMD_DEBUG2 (("Search element e "ID" in me "ID"\n", e,me)) ; + ASSERT (Elen [e] < EMPTY && W [e] > 0 && pj >= 0) ; + } + ASSERT (ln >= 0 && (ln == 0 || (pj >= 0 && pj < iwlen))) ; + + /* --------------------------------------------------------- + * search for different supervariables and add them to the + * new list, compressing when necessary. this loop is + * executed once for each element in the list and once for + * all the supervariables in the list. + * --------------------------------------------------------- */ + + for (knt2 = 1 ; knt2 <= ln ; knt2++) + { + i = Iw [pj++] ; + ASSERT (i >= 0 && i < n && (i == me || Elen [i] >= EMPTY)); + nvi = Nv [i] ; + AMD_DEBUG2 ((": "ID" "ID" "ID" "ID"\n", + i, Elen [i], Nv [i], wflg)) ; + + if (nvi > 0) + { + + /* ------------------------------------------------- */ + /* compress Iw, if necessary */ + /* ------------------------------------------------- */ + + if (pfree >= iwlen) + { + + AMD_DEBUG1 (("GARBAGE COLLECTION\n")) ; + + /* prepare for compressing Iw by adjusting pointers + * and lengths so that the lists being searched in + * the inner and outer loops contain only the + * remaining entries. */ + + Pe [me] = p ; + Len [me] -= knt1 ; + /* check if nothing left of supervariable me */ + if (Len [me] == 0) Pe [me] = EMPTY ; + Pe [e] = pj ; + Len [e] = ln - knt2 ; + /* nothing left of element e */ + if (Len [e] == 0) Pe [e] = EMPTY ; + + ncmpa++ ; /* one more garbage collection */ + + /* store first entry of each object in Pe */ + /* FLIP the first entry in each object */ + for (j = 0 ; j < n ; j++) + { + pn = Pe [j] ; + if (pn >= 0) + { + ASSERT (pn >= 0 && pn < iwlen) ; + Pe [j] = Iw [pn] ; + Iw [pn] = FLIP (j) ; + } + } + + /* psrc/pdst point to source/destination */ + psrc = 0 ; + pdst = 0 ; + pend = pme1 - 1 ; + + while (psrc <= pend) + { + /* search for next FLIP'd entry */ + j = FLIP (Iw [psrc++]) ; + if (j >= 0) + { + AMD_DEBUG2 (("Got object j: "ID"\n", j)) ; + Iw [pdst] = Pe [j] ; + Pe [j] = pdst++ ; + lenj = Len [j] ; + /* copy from source to destination */ + for (knt3 = 0 ; knt3 <= lenj - 2 ; knt3++) + { + Iw [pdst++] = Iw [psrc++] ; + } + } + } + + /* move the new partially-constructed element */ + p1 = pdst ; + for (psrc = pme1 ; psrc <= pfree-1 ; psrc++) + { + Iw [pdst++] = Iw [psrc] ; + } + pme1 = p1 ; + pfree = pdst ; + pj = Pe [e] ; + p = Pe [me] ; + + } + + /* ------------------------------------------------- */ + /* i is a principal variable not yet placed in Lme */ + /* store i in new list */ + /* ------------------------------------------------- */ + + /* flag i as being in Lme by negating Nv [i] */ + degme += nvi ; + Nv [i] = -nvi ; + Iw [pfree++] = i ; + AMD_DEBUG2 ((" s: "ID" nv "ID"\n", i, Nv [i])); + + /* ------------------------------------------------- */ + /* remove variable i from degree link list */ + /* ------------------------------------------------- */ + + ilast = Last [i] ; + inext = Next [i] ; + ASSERT (ilast >= EMPTY && ilast < n) ; + ASSERT (inext >= EMPTY && inext < n) ; + if (inext != EMPTY) Last [inext] = ilast ; + if (ilast != EMPTY) + { + Next [ilast] = inext ; + } + else + { + /* i is at the head of the degree list */ + ASSERT (Degree [i] >= 0 && Degree [i] < n) ; + Head [Degree [i]] = inext ; + } + } + } + + if (e != me) + { + /* set tree pointer and flag to indicate element e is + * absorbed into new element me (the parent of e is me) */ + AMD_DEBUG1 ((" Element "ID" => "ID"\n", e, me)) ; + Pe [e] = FLIP (me) ; + W [e] = 0 ; + } + } + + pme2 = pfree - 1 ; + } + + /* ----------------------------------------------------------------- */ + /* me has now been converted into an element in Iw [pme1..pme2] */ + /* ----------------------------------------------------------------- */ + + /* degme holds the external degree of new element */ + Degree [me] = degme ; + Pe [me] = pme1 ; + Len [me] = pme2 - pme1 + 1 ; + ASSERT (Pe [me] >= 0 && Pe [me] < iwlen) ; + + Elen [me] = FLIP (nvpiv + degme) ; + /* FLIP (Elen (me)) is now the degree of pivot (including + * diagonal part). */ + +#ifndef NDEBUG + AMD_DEBUG2 (("New element structure: length= "ID"\n", pme2-pme1+1)) ; + for (pme = pme1 ; pme <= pme2 ; pme++) AMD_DEBUG3 ((" "ID"", Iw[pme])); + AMD_DEBUG3 (("\n")) ; +#endif + + /* ----------------------------------------------------------------- */ + /* make sure that wflg is not too large. */ + /* ----------------------------------------------------------------- */ + + /* With the current value of wflg, wflg+n must not cause integer + * overflow */ + + wflg = clear_flag (wflg, wbig, W, n) ; + +/* ========================================================================= */ +/* COMPUTE (W [e] - wflg) = |Le\Lme| FOR ALL ELEMENTS */ +/* ========================================================================= */ + + /* ----------------------------------------------------------------- + * Scan 1: compute the external degrees of previous elements with + * respect to the current element. That is: + * (W [e] - wflg) = |Le \ Lme| + * for each element e that appears in any supervariable in Lme. The + * notation Le refers to the pattern (list of supervariables) of a + * previous element e, where e is not yet absorbed, stored in + * Iw [Pe [e] + 1 ... Pe [e] + Len [e]]. The notation Lme + * refers to the pattern of the current element (stored in + * Iw [pme1..pme2]). If aggressive absorption is enabled, and + * (W [e] - wflg) becomes zero, then the element e will be absorbed + * in Scan 2. + * ----------------------------------------------------------------- */ + + AMD_DEBUG2 (("me: ")) ; + for (pme = pme1 ; pme <= pme2 ; pme++) + { + i = Iw [pme] ; + ASSERT (i >= 0 && i < n) ; + eln = Elen [i] ; + AMD_DEBUG3 ((""ID" Elen "ID": \n", i, eln)) ; + if (eln > 0) + { + /* note that Nv [i] has been negated to denote i in Lme: */ + nvi = -Nv [i] ; + ASSERT (nvi > 0 && Pe [i] >= 0 && Pe [i] < iwlen) ; + wnvi = wflg - nvi ; + for (p = Pe [i] ; p <= Pe [i] + eln - 1 ; p++) + { + e = Iw [p] ; + ASSERT (e >= 0 && e < n) ; + we = W [e] ; + AMD_DEBUG4 ((" e "ID" we "ID" ", e, we)) ; + if (we >= wflg) + { + /* unabsorbed element e has been seen in this loop */ + AMD_DEBUG4 ((" unabsorbed, first time seen")) ; + we -= nvi ; + } + else if (we != 0) + { + /* e is an unabsorbed element */ + /* this is the first we have seen e in all of Scan 1 */ + AMD_DEBUG4 ((" unabsorbed")) ; + we = Degree [e] + wnvi ; + } + AMD_DEBUG4 (("\n")) ; + W [e] = we ; + } + } + } + AMD_DEBUG2 (("\n")) ; + +/* ========================================================================= */ +/* DEGREE UPDATE AND ELEMENT ABSORPTION */ +/* ========================================================================= */ + + /* ----------------------------------------------------------------- + * Scan 2: for each i in Lme, sum up the degree of Lme (which is + * degme), plus the sum of the external degrees of each Le for the + * elements e appearing within i, plus the supervariables in i. + * Place i in hash list. + * ----------------------------------------------------------------- */ + + for (pme = pme1 ; pme <= pme2 ; pme++) + { + i = Iw [pme] ; + ASSERT (i >= 0 && i < n && Nv [i] < 0 && Elen [i] >= 0) ; + AMD_DEBUG2 (("Updating: i "ID" "ID" "ID"\n", i, Elen[i], Len [i])); + p1 = Pe [i] ; + p2 = p1 + Elen [i] - 1 ; + pn = p1 ; + hash = 0 ; + deg = 0 ; + ASSERT (p1 >= 0 && p1 < iwlen && p2 >= -1 && p2 < iwlen) ; + + /* ------------------------------------------------------------- */ + /* scan the element list associated with supervariable i */ + /* ------------------------------------------------------------- */ + + /* UMFPACK/MA38-style approximate degree: */ + if (aggressive) + { + for (p = p1 ; p <= p2 ; p++) + { + e = Iw [p] ; + ASSERT (e >= 0 && e < n) ; + we = W [e] ; + if (we != 0) + { + /* e is an unabsorbed element */ + /* dext = | Le \ Lme | */ + dext = we - wflg ; + if (dext > 0) + { + deg += dext ; + Iw [pn++] = e ; + hash += e ; + AMD_DEBUG4 ((" e: "ID" hash = "ID"\n",e,hash)) ; + } + else + { + /* external degree of e is zero, absorb e into me*/ + AMD_DEBUG1 ((" Element "ID" =>"ID" (aggressive)\n", + e, me)) ; + ASSERT (dext == 0) ; + Pe [e] = FLIP (me) ; + W [e] = 0 ; + } + } + } + } + else + { + for (p = p1 ; p <= p2 ; p++) + { + e = Iw [p] ; + ASSERT (e >= 0 && e < n) ; + we = W [e] ; + if (we != 0) + { + /* e is an unabsorbed element */ + dext = we - wflg ; + ASSERT (dext >= 0) ; + deg += dext ; + Iw [pn++] = e ; + hash += e ; + AMD_DEBUG4 ((" e: "ID" hash = "ID"\n",e,hash)) ; + } + } + } + + /* count the number of elements in i (including me): */ + Elen [i] = pn - p1 + 1 ; + + /* ------------------------------------------------------------- */ + /* scan the supervariables in the list associated with i */ + /* ------------------------------------------------------------- */ + + /* The bulk of the AMD run time is typically spent in this loop, + * particularly if the matrix has many dense rows that are not + * removed prior to ordering. */ + p3 = pn ; + p4 = p1 + Len [i] ; + for (p = p2 + 1 ; p < p4 ; p++) + { + j = Iw [p] ; + ASSERT (j >= 0 && j < n) ; + nvj = Nv [j] ; + if (nvj > 0) + { + /* j is unabsorbed, and not in Lme. */ + /* add to degree and add to new list */ + deg += nvj ; + Iw [pn++] = j ; + hash += j ; + AMD_DEBUG4 ((" s: "ID" hash "ID" Nv[j]= "ID"\n", + j, hash, nvj)) ; + } + } + + /* ------------------------------------------------------------- */ + /* update the degree and check for mass elimination */ + /* ------------------------------------------------------------- */ + + /* with aggressive absorption, deg==0 is identical to the + * Elen [i] == 1 && p3 == pn test, below. */ + ASSERT (IMPLIES (aggressive, (deg==0) == (Elen[i]==1 && p3==pn))) ; + + if (Elen [i] == 1 && p3 == pn) + { + + /* --------------------------------------------------------- */ + /* mass elimination */ + /* --------------------------------------------------------- */ + + /* There is nothing left of this node except for an edge to + * the current pivot element. Elen [i] is 1, and there are + * no variables adjacent to node i. Absorb i into the + * current pivot element, me. Note that if there are two or + * more mass eliminations, fillin due to mass elimination is + * possible within the nvpiv-by-nvpiv pivot block. It is this + * step that causes AMD's analysis to be an upper bound. + * + * The reason is that the selected pivot has a lower + * approximate degree than the true degree of the two mass + * eliminated nodes. There is no edge between the two mass + * eliminated nodes. They are merged with the current pivot + * anyway. + * + * No fillin occurs in the Schur complement, in any case, + * and this effect does not decrease the quality of the + * ordering itself, just the quality of the nonzero and + * flop count analysis. It also means that the post-ordering + * is not an exact elimination tree post-ordering. */ + + AMD_DEBUG1 ((" MASS i "ID" => parent e "ID"\n", i, me)) ; + Pe [i] = FLIP (me) ; + nvi = -Nv [i] ; + degme -= nvi ; + nvpiv += nvi ; + nel += nvi ; + Nv [i] = 0 ; + Elen [i] = EMPTY ; + + } + else + { + + /* --------------------------------------------------------- */ + /* update the upper-bound degree of i */ + /* --------------------------------------------------------- */ + + /* the following degree does not yet include the size + * of the current element, which is added later: */ + + Degree [i] = MIN (Degree [i], deg) ; + + /* --------------------------------------------------------- */ + /* add me to the list for i */ + /* --------------------------------------------------------- */ + + /* move first supervariable to end of list */ + Iw [pn] = Iw [p3] ; + /* move first element to end of element part of list */ + Iw [p3] = Iw [p1] ; + /* add new element, me, to front of list. */ + Iw [p1] = me ; + /* store the new length of the list in Len [i] */ + Len [i] = pn - p1 + 1 ; + + /* --------------------------------------------------------- */ + /* place in hash bucket. Save hash key of i in Last [i]. */ + /* --------------------------------------------------------- */ + + /* NOTE: this can fail if hash is negative, because the ANSI C + * standard does not define a % b when a and/or b are negative. + * That's why hash is defined as an unsigned Int, to avoid this + * problem. */ + hash = hash % n ; + ASSERT (((Int) hash) >= 0 && ((Int) hash) < n) ; + + /* if the Hhead array is not used: */ + j = Head [hash] ; + if (j <= EMPTY) + { + /* degree list is empty, hash head is FLIP (j) */ + Next [i] = FLIP (j) ; + Head [hash] = FLIP (i) ; + } + else + { + /* degree list is not empty, use Last [Head [hash]] as + * hash head. */ + Next [i] = Last [j] ; + Last [j] = i ; + } + + /* if a separate Hhead array is used: * + Next [i] = Hhead [hash] ; + Hhead [hash] = i ; + */ + + Last [i] = hash ; + } + } + + Degree [me] = degme ; + + /* ----------------------------------------------------------------- */ + /* Clear the counter array, W [...], by incrementing wflg. */ + /* ----------------------------------------------------------------- */ + + /* make sure that wflg+n does not cause integer overflow */ + lemax = MAX (lemax, degme) ; + wflg += lemax ; + wflg = clear_flag (wflg, wbig, W, n) ; + /* at this point, W [0..n-1] < wflg holds */ + +/* ========================================================================= */ +/* SUPERVARIABLE DETECTION */ +/* ========================================================================= */ + + AMD_DEBUG1 (("Detecting supervariables:\n")) ; + for (pme = pme1 ; pme <= pme2 ; pme++) + { + i = Iw [pme] ; + ASSERT (i >= 0 && i < n) ; + AMD_DEBUG2 (("Consider i "ID" nv "ID"\n", i, Nv [i])) ; + if (Nv [i] < 0) + { + /* i is a principal variable in Lme */ + + /* --------------------------------------------------------- + * examine all hash buckets with 2 or more variables. We do + * this by examing all unique hash keys for supervariables in + * the pattern Lme of the current element, me + * --------------------------------------------------------- */ + + /* let i = head of hash bucket, and empty the hash bucket */ + ASSERT (Last [i] >= 0 && Last [i] < n) ; + hash = Last [i] ; + + /* if Hhead array is not used: */ + j = Head [hash] ; + if (j == EMPTY) + { + /* hash bucket and degree list are both empty */ + i = EMPTY ; + } + else if (j < EMPTY) + { + /* degree list is empty */ + i = FLIP (j) ; + Head [hash] = EMPTY ; + } + else + { + /* degree list is not empty, restore Last [j] of head j */ + i = Last [j] ; + Last [j] = EMPTY ; + } + + /* if separate Hhead array is used: * + i = Hhead [hash] ; + Hhead [hash] = EMPTY ; + */ + + ASSERT (i >= EMPTY && i < n) ; + AMD_DEBUG2 (("----i "ID" hash "ID"\n", i, hash)) ; + + while (i != EMPTY && Next [i] != EMPTY) + { + + /* ----------------------------------------------------- + * this bucket has one or more variables following i. + * scan all of them to see if i can absorb any entries + * that follow i in hash bucket. Scatter i into w. + * ----------------------------------------------------- */ + + ln = Len [i] ; + eln = Elen [i] ; + ASSERT (ln >= 0 && eln >= 0) ; + ASSERT (Pe [i] >= 0 && Pe [i] < iwlen) ; + /* do not flag the first element in the list (me) */ + for (p = Pe [i] + 1 ; p <= Pe [i] + ln - 1 ; p++) + { + ASSERT (Iw [p] >= 0 && Iw [p] < n) ; + W [Iw [p]] = wflg ; + } + + /* ----------------------------------------------------- */ + /* scan every other entry j following i in bucket */ + /* ----------------------------------------------------- */ + + jlast = i ; + j = Next [i] ; + ASSERT (j >= EMPTY && j < n) ; + + while (j != EMPTY) + { + /* ------------------------------------------------- */ + /* check if j and i have identical nonzero pattern */ + /* ------------------------------------------------- */ + + AMD_DEBUG3 (("compare i "ID" and j "ID"\n", i,j)) ; + + /* check if i and j have the same Len and Elen */ + ASSERT (Len [j] >= 0 && Elen [j] >= 0) ; + ASSERT (Pe [j] >= 0 && Pe [j] < iwlen) ; + ok = (Len [j] == ln) && (Elen [j] == eln) ; + /* skip the first element in the list (me) */ + for (p = Pe [j] + 1 ; ok && p <= Pe [j] + ln - 1 ; p++) + { + ASSERT (Iw [p] >= 0 && Iw [p] < n) ; + if (W [Iw [p]] != wflg) ok = 0 ; + } + if (ok) + { + /* --------------------------------------------- */ + /* found it! j can be absorbed into i */ + /* --------------------------------------------- */ + + AMD_DEBUG1 (("found it! j "ID" => i "ID"\n", j,i)); + Pe [j] = FLIP (i) ; + /* both Nv [i] and Nv [j] are negated since they */ + /* are in Lme, and the absolute values of each */ + /* are the number of variables in i and j: */ + Nv [i] += Nv [j] ; + Nv [j] = 0 ; + Elen [j] = EMPTY ; + /* delete j from hash bucket */ + ASSERT (j != Next [j]) ; + j = Next [j] ; + Next [jlast] = j ; + + } + else + { + /* j cannot be absorbed into i */ + jlast = j ; + ASSERT (j != Next [j]) ; + j = Next [j] ; + } + ASSERT (j >= EMPTY && j < n) ; + } + + /* ----------------------------------------------------- + * no more variables can be absorbed into i + * go to next i in bucket and clear flag array + * ----------------------------------------------------- */ + + wflg++ ; + i = Next [i] ; + ASSERT (i >= EMPTY && i < n) ; + + } + } + } + AMD_DEBUG2 (("detect done\n")) ; + +/* ========================================================================= */ +/* RESTORE DEGREE LISTS AND REMOVE NONPRINCIPAL SUPERVARIABLES FROM ELEMENT */ +/* ========================================================================= */ + + p = pme1 ; + nleft = n - nel ; + for (pme = pme1 ; pme <= pme2 ; pme++) + { + i = Iw [pme] ; + ASSERT (i >= 0 && i < n) ; + nvi = -Nv [i] ; + AMD_DEBUG3 (("Restore i "ID" "ID"\n", i, nvi)) ; + if (nvi > 0) + { + /* i is a principal variable in Lme */ + /* restore Nv [i] to signify that i is principal */ + Nv [i] = nvi ; + + /* --------------------------------------------------------- */ + /* compute the external degree (add size of current element) */ + /* --------------------------------------------------------- */ + + deg = Degree [i] + degme - nvi ; + deg = MIN (deg, nleft - nvi) ; + ASSERT (IMPLIES (aggressive, deg > 0) && deg >= 0 && deg < n) ; + + /* --------------------------------------------------------- */ + /* place the supervariable at the head of the degree list */ + /* --------------------------------------------------------- */ + + inext = Head [deg] ; + ASSERT (inext >= EMPTY && inext < n) ; + if (inext != EMPTY) Last [inext] = i ; + Next [i] = inext ; + Last [i] = EMPTY ; + Head [deg] = i ; + + /* --------------------------------------------------------- */ + /* save the new degree, and find the minimum degree */ + /* --------------------------------------------------------- */ + + mindeg = MIN (mindeg, deg) ; + Degree [i] = deg ; + + /* --------------------------------------------------------- */ + /* place the supervariable in the element pattern */ + /* --------------------------------------------------------- */ + + Iw [p++] = i ; + + } + } + AMD_DEBUG2 (("restore done\n")) ; + +/* ========================================================================= */ +/* FINALIZE THE NEW ELEMENT */ +/* ========================================================================= */ + + AMD_DEBUG2 (("ME = "ID" DONE\n", me)) ; + Nv [me] = nvpiv ; + /* save the length of the list for the new element me */ + Len [me] = p - pme1 ; + if (Len [me] == 0) + { + /* there is nothing left of the current pivot element */ + /* it is a root of the assembly tree */ + Pe [me] = EMPTY ; + W [me] = 0 ; + } + if (elenme != 0) + { + /* element was not constructed in place: deallocate part of */ + /* it since newly nonprincipal variables may have been removed */ + pfree = p ; + } + + /* The new element has nvpiv pivots and the size of the contribution + * block for a multifrontal method is degme-by-degme, not including + * the "dense" rows/columns. If the "dense" rows/columns are included, + * the frontal matrix is no larger than + * (degme+ndense)-by-(degme+ndense). + */ + + if (Info != (double *) NULL) + { + f = nvpiv ; + r = degme + ndense ; + dmax = MAX (dmax, f + r) ; + + /* number of nonzeros in L (excluding the diagonal) */ + lnzme = f*r + (f-1)*f/2 ; + lnz += lnzme ; + + /* number of divide operations for LDL' and for LU */ + ndiv += lnzme ; + + /* number of multiply-subtract pairs for LU */ + s = f*r*r + r*(f-1)*f + (f-1)*f*(2*f-1)/6 ; + nms_lu += s ; + + /* number of multiply-subtract pairs for LDL' */ + nms_ldl += (s + lnzme)/2 ; + } + +#ifndef NDEBUG + AMD_DEBUG2 (("finalize done nel "ID" n "ID"\n ::::\n", nel, n)) ; + for (pme = Pe [me] ; pme <= Pe [me] + Len [me] - 1 ; pme++) + { + AMD_DEBUG3 ((" "ID"", Iw [pme])) ; + } + AMD_DEBUG3 (("\n")) ; +#endif + + } + +/* ========================================================================= */ +/* DONE SELECTING PIVOTS */ +/* ========================================================================= */ + + if (Info != (double *) NULL) + { + + /* count the work to factorize the ndense-by-ndense submatrix */ + f = ndense ; + dmax = MAX (dmax, (double) ndense) ; + + /* number of nonzeros in L (excluding the diagonal) */ + lnzme = (f-1)*f/2 ; + lnz += lnzme ; + + /* number of divide operations for LDL' and for LU */ + ndiv += lnzme ; + + /* number of multiply-subtract pairs for LU */ + s = (f-1)*f*(2*f-1)/6 ; + nms_lu += s ; + + /* number of multiply-subtract pairs for LDL' */ + nms_ldl += (s + lnzme)/2 ; + + /* number of nz's in L (excl. diagonal) */ + Info [AMD_LNZ] = lnz ; + + /* number of divide ops for LU and LDL' */ + Info [AMD_NDIV] = ndiv ; + + /* number of multiply-subtract pairs for LDL' */ + Info [AMD_NMULTSUBS_LDL] = nms_ldl ; + + /* number of multiply-subtract pairs for LU */ + Info [AMD_NMULTSUBS_LU] = nms_lu ; + + /* number of "dense" rows/columns */ + Info [AMD_NDENSE] = ndense ; + + /* largest front is dmax-by-dmax */ + Info [AMD_DMAX] = dmax ; + + /* number of garbage collections in AMD */ + Info [AMD_NCMPA] = ncmpa ; + + /* successful ordering */ + Info [AMD_STATUS] = AMD_OK ; + } + +/* ========================================================================= */ +/* POST-ORDERING */ +/* ========================================================================= */ + +/* ------------------------------------------------------------------------- + * Variables at this point: + * + * Pe: holds the elimination tree. The parent of j is FLIP (Pe [j]), + * or EMPTY if j is a root. The tree holds both elements and + * non-principal (unordered) variables absorbed into them. + * Dense variables are non-principal and unordered. + * + * Elen: holds the size of each element, including the diagonal part. + * FLIP (Elen [e]) > 0 if e is an element. For unordered + * variables i, Elen [i] is EMPTY. + * + * Nv: Nv [e] > 0 is the number of pivots represented by the element e. + * For unordered variables i, Nv [i] is zero. + * + * Contents no longer needed: + * W, Iw, Len, Degree, Head, Next, Last. + * + * The matrix itself has been destroyed. + * + * n: the size of the matrix. + * No other scalars needed (pfree, iwlen, etc.) + * ------------------------------------------------------------------------- */ + + /* restore Pe */ + for (i = 0 ; i < n ; i++) + { + Pe [i] = FLIP (Pe [i]) ; + } + + /* restore Elen, for output information, and for postordering */ + for (i = 0 ; i < n ; i++) + { + Elen [i] = FLIP (Elen [i]) ; + } + +/* Now the parent of j is Pe [j], or EMPTY if j is a root. Elen [e] > 0 + * is the size of element e. Elen [i] is EMPTY for unordered variable i. */ + +#ifndef NDEBUG + AMD_DEBUG2 (("\nTree:\n")) ; + for (i = 0 ; i < n ; i++) + { + AMD_DEBUG2 ((" "ID" parent: "ID" ", i, Pe [i])) ; + ASSERT (Pe [i] >= EMPTY && Pe [i] < n) ; + if (Nv [i] > 0) + { + /* this is an element */ + e = i ; + AMD_DEBUG2 ((" element, size is "ID"\n", Elen [i])) ; + ASSERT (Elen [e] > 0) ; + } + AMD_DEBUG2 (("\n")) ; + } + AMD_DEBUG2 (("\nelements:\n")) ; + for (e = 0 ; e < n ; e++) + { + if (Nv [e] > 0) + { + AMD_DEBUG3 (("Element e= "ID" size "ID" nv "ID" \n", e, + Elen [e], Nv [e])) ; + } + } + AMD_DEBUG2 (("\nvariables:\n")) ; + for (i = 0 ; i < n ; i++) + { + Int cnt ; + if (Nv [i] == 0) + { + AMD_DEBUG3 (("i unordered: "ID"\n", i)) ; + j = Pe [i] ; + cnt = 0 ; + AMD_DEBUG3 ((" j: "ID"\n", j)) ; + if (j == EMPTY) + { + AMD_DEBUG3 ((" i is a dense variable\n")) ; + } + else + { + ASSERT (j >= 0 && j < n) ; + while (Nv [j] == 0) + { + AMD_DEBUG3 ((" j : "ID"\n", j)) ; + j = Pe [j] ; + AMD_DEBUG3 ((" j:: "ID"\n", j)) ; + cnt++ ; + if (cnt > n) break ; + } + e = j ; + AMD_DEBUG3 ((" got to e: "ID"\n", e)) ; + } + } + } +#endif + +/* ========================================================================= */ +/* compress the paths of the variables */ +/* ========================================================================= */ + + for (i = 0 ; i < n ; i++) + { + if (Nv [i] == 0) + { + + /* ------------------------------------------------------------- + * i is an un-ordered row. Traverse the tree from i until + * reaching an element, e. The element, e, was the principal + * supervariable of i and all nodes in the path from i to when e + * was selected as pivot. + * ------------------------------------------------------------- */ + + AMD_DEBUG1 (("Path compression, i unordered: "ID"\n", i)) ; + j = Pe [i] ; + ASSERT (j >= EMPTY && j < n) ; + AMD_DEBUG3 ((" j: "ID"\n", j)) ; + if (j == EMPTY) + { + /* Skip a dense variable. It has no parent. */ + AMD_DEBUG3 ((" i is a dense variable\n")) ; + continue ; + } + + /* while (j is a variable) */ + while (Nv [j] == 0) + { + AMD_DEBUG3 ((" j : "ID"\n", j)) ; + j = Pe [j] ; + AMD_DEBUG3 ((" j:: "ID"\n", j)) ; + ASSERT (j >= 0 && j < n) ; + } + /* got to an element e */ + e = j ; + AMD_DEBUG3 (("got to e: "ID"\n", e)) ; + + /* ------------------------------------------------------------- + * traverse the path again from i to e, and compress the path + * (all nodes point to e). Path compression allows this code to + * compute in O(n) time. + * ------------------------------------------------------------- */ + + j = i ; + /* while (j is a variable) */ + while (Nv [j] == 0) + { + jnext = Pe [j] ; + AMD_DEBUG3 (("j "ID" jnext "ID"\n", j, jnext)) ; + Pe [j] = e ; + j = jnext ; + ASSERT (j >= 0 && j < n) ; + } + } + } + +/* ========================================================================= */ +/* postorder the assembly tree */ +/* ========================================================================= */ + + AMD_postorder (n, Pe, Nv, Elen, + W, /* output order */ + Head, Next, Last) ; /* workspace */ + +/* ========================================================================= */ +/* compute output permutation and inverse permutation */ +/* ========================================================================= */ + + /* W [e] = k means that element e is the kth element in the new + * order. e is in the range 0 to n-1, and k is in the range 0 to + * the number of elements. Use Head for inverse order. */ + + for (k = 0 ; k < n ; k++) + { + Head [k] = EMPTY ; + Next [k] = EMPTY ; + } + for (e = 0 ; e < n ; e++) + { + k = W [e] ; + ASSERT ((k == EMPTY) == (Nv [e] == 0)) ; + if (k != EMPTY) + { + ASSERT (k >= 0 && k < n) ; + Head [k] = e ; + } + } + + /* construct output inverse permutation in Next, + * and permutation in Last */ + nel = 0 ; + for (k = 0 ; k < n ; k++) + { + e = Head [k] ; + if (e == EMPTY) break ; + ASSERT (e >= 0 && e < n && Nv [e] > 0) ; + Next [e] = nel ; + nel += Nv [e] ; + } + ASSERT (nel == n - ndense) ; + + /* order non-principal variables (dense, & those merged into supervar's) */ + for (i = 0 ; i < n ; i++) + { + if (Nv [i] == 0) + { + e = Pe [i] ; + ASSERT (e >= EMPTY && e < n) ; + if (e != EMPTY) + { + /* This is an unordered variable that was merged + * into element e via supernode detection or mass + * elimination of i when e became the pivot element. + * Place i in order just before e. */ + ASSERT (Next [i] == EMPTY && Nv [e] > 0) ; + Next [i] = Next [e] ; + Next [e]++ ; + } + else + { + /* This is a dense unordered variable, with no parent. + * Place it last in the output order. */ + Next [i] = nel++ ; + } + } + } + ASSERT (nel == n) ; + + AMD_DEBUG2 (("\n\nPerm:\n")) ; + for (i = 0 ; i < n ; i++) + { + k = Next [i] ; + ASSERT (k >= 0 && k < n) ; + Last [k] = i ; + AMD_DEBUG2 ((" perm ["ID"] = "ID"\n", k, i)) ; + } +} |