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/* For copyright information, see olden_v1.0/COPYRIGHT */
#include "defines.h"
/****************************************************************/
/* Vector Routines. */
/* From CMU vision library. */
/* They are used only for the VD, not the DT. */
/* They are slow because of large call-by-value parameters.*/
/****************************************************************/
/* V2_cprod: forms triple scalar product of [u,v,k], where k = u cross v */
/* (returns the magnitude of u cross v in space)*/
double V2_cprod(u,v)
struct VEC2 u,v;
{
return(u.x * v.y - u.y * v.x);
}
/* V2_dot: vector dot product */
double V2_dot(u,v)
struct VEC2 u,v;
{
return(u.x * v.x + u.y * v.y);
}
/* V2_times: multiply a vector by a scalar */
struct VEC2 V2_times(c,v)
double c;
struct VEC2 v;
{
struct VEC2 ans;
ans.x = c * v.x;
ans.y = c * v.y;
return(ans);
}
/* V2_sum, V2_sub: Vector addition and subtraction */
struct VEC2 V2_sum(u,v)
struct VEC2 u,v;
{
struct VEC2 ans;
ans.x = u.x + v.x;
ans.y = u.y + v.y;
return(ans);
}
struct VEC2 V2_sub(u,v)
struct VEC2 u,v;
{
struct VEC2 ans;
ans.x = u.x - v.x;
ans.y = u.y - v.y;
return(ans);
}
/* V2_magn: magnitude of vector */
double V2_magn(u)
struct VEC2 u;
{
return(sqrt(u.x*u.x+u.y*u.y));
}
/* returns k X v (cross product). this is a vector perpendicular to v */
struct VEC2 V2_cross(v)
struct VEC2 v;
{
struct VEC2 ans;
ans.x = v.y;
ans.y = -v.x;
return(ans);
}
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