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/* fvs.c (sparse vector in FVS format) */
/***********************************************************************
* This code is part of GLPK (GNU Linear Programming Kit).
*
* Copyright (C) 2016 Andrew Makhorin, Department for Applied
* Informatics, Moscow Aviation Institute, Moscow, Russia. All rights
* reserved. E-mail: <mao@gnu.org>.
*
* GLPK is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GLPK is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
* License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GLPK. If not, see <http://www.gnu.org/licenses/>.
***********************************************************************/
#include "env.h"
#include "fvs.h"
void fvs_alloc_vec(FVS *x, int n)
{ /* allocate sparse vector */
int j;
xassert(n >= 0);
x->n = n;
x->nnz = 0;
x->ind = talloc(1+n, int);
x->vec = talloc(1+n, double);
for (j = 1; j <= n; j++)
x->vec[j] = 0.0;
return;
}
void fvs_check_vec(const FVS *x)
{ /* check sparse vector */
/* NOTE: for testing/debugging only */
int n = x->n;
int nnz = x->nnz;
int *ind = x->ind;
double *vec = x->vec;
char *map;
int j, k;
xassert(n >= 0);
xassert(0 <= nnz && nnz <= n);
map = talloc(1+n, char);
for (j = 1; j <= n; j++)
map[j] = (vec[j] != 0.0);
for (k = 1; k <= nnz; k++)
{ j = ind[k];
xassert(1 <= j && j <= n);
xassert(map[j]);
map[j] = 0;
}
for (j = 1; j <= n; j++)
xassert(!map[j]);
tfree(map);
return;
}
void fvs_gather_vec(FVS *x, double eps)
{ /* gather sparse vector */
int n = x->n;
int *ind = x->ind;
double *vec = x->vec;
int j, nnz = 0;
for (j = n; j >= 1; j--)
{ if (-eps < vec[j] && vec[j] < +eps)
vec[j] = 0.0;
else
ind[++nnz] = j;
}
x->nnz = nnz;
return;
}
void fvs_clear_vec(FVS *x)
{ /* clear sparse vector */
int *ind = x->ind;
double *vec = x->vec;
int k;
for (k = x->nnz; k >= 1; k--)
vec[ind[k]] = 0.0;
x->nnz = 0;
return;
}
void fvs_copy_vec(FVS *x, const FVS *y)
{ /* copy sparse vector */
int *x_ind = x->ind;
double *x_vec = x->vec;
int *y_ind = y->ind;
double *y_vec = y->vec;
int j, k;
xassert(x != y);
xassert(x->n == y->n);
fvs_clear_vec(x);
for (k = x->nnz = y->nnz; k >= 1; k--)
{ j = x_ind[k] = y_ind[k];
x_vec[j] = y_vec[j];
}
return;
}
void fvs_adjust_vec(FVS *x, double eps)
{ /* replace tiny vector elements by exact zeros */
int nnz = x->nnz;
int *ind = x->ind;
double *vec = x->vec;
int j, k, cnt = 0;
for (k = 1; k <= nnz; k++)
{ j = ind[k];
if (-eps < vec[j] && vec[j] < +eps)
vec[j] = 0.0;
else
ind[++cnt] = j;
}
x->nnz = cnt;
return;
}
void fvs_free_vec(FVS *x)
{ /* deallocate sparse vector */
tfree(x->ind);
tfree(x->vec);
x->n = x->nnz = -1;
x->ind = NULL;
x->vec = NULL;
return;
}
/* eof */
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