1 #include "cs.h"
2 /* pinv = p', or p = pinv' */
cs_pinv(CS_INT const * p,CS_INT n)3 CS_INT *cs_pinv (CS_INT const *p, CS_INT n)
4 {
5     CS_INT k, *pinv ;
6     if (!p) return (NULL) ;                     /* p = NULL denotes identity */
7     pinv = cs_malloc (n, sizeof (CS_INT)) ;        /* allocate result */
8     if (!pinv) return (NULL) ;                  /* out of memory */
9     for (k = 0 ; k < n ; k++) pinv [p [k]] = k ;/* invert the permutation */
10     return (pinv) ;                             /* return result */
11 }
12