HPL_perm - Man Page

Combine 2 index arrays — Generate the permutation.


#include "hpl.h"
 void HPL_perm( const int N, int * LINDXA, int * LINDXAU, int * IWORK );


HPL_perm combines  two  index  arrays  and generate the corresponding permutation. First, this function computes the inverse of LINDXA, and then combine it with LINDXAU.  Second, in order to be able to perform the permutation in place,  LINDXAU  is overwritten by the sequence of permutation  producing  the  same result.  What we ultimately want to achieve is:  U[LINDXAU[i]] := U[LINDXA[i]] for i in [0..N). After the call to this function,  this in place permutation can be performed by for i in [0..N) swap U[i] with U[LINDXAU[i]].


N       (global input)          const int

On entry,  N  specifies the length of the arrays  LINDXA  and LINDXAU. N should be at least zero.

LINDXA  (global input/output)   int *

On entry,  LINDXA  is an array of dimension N  containing the source indexes. On exit,  LINDXA  contains the combined index array.

LINDXAU (global input/output)   int *

On entry,  LINDXAU is an array of dimension N  containing the target indexes.  On exit,  LINDXAU  contains  the sequence of permutation,  that  should be applied  in increasing order to permute the underlying array U in place.

IWORK   (workspace)             int *

On entry, IWORK is a workarray of dimension N.

See Also

HPL_plindx1 (3), HPL_pdlaswp01N (3), HPL_pdlaswp01T (3).


February 24, 2016 HPL 2.2 HPL Library Functions