HPL_pdmxswp man page

HPL_pdmxswp — swaps and broacast the pivot row.


#include "hpl.h"
 void HPL_pdmxswp( HPL_T_panel * PANEL, const int M, const int II, const int JJ, double * WORK );


HPL_pdmxswp swaps  and  broadcasts  the  absolute value max row using bi-directional exchange.  The buffer is partially set by HPL_dlocmax.
 Bi-directional  exchange  is  used  to  perform  the  swap::broadcast operations  at once  for one column in the panel.  This  results in a lower number of slightly larger  messages than usual.  On P processes and assuming bi-directional links,  the running time of this function can be approximated by

  log_2( P ) * ( lat + ( 2 * N0 + 4 ) / bdwth )
 where  lat and bdwth are the latency and bandwidth of the network for double precision real elements.  Communication  only  occurs  in  one process  column. Mono-directional links  will cause the communication cost to double.


PANEL   (local input/output)    HPL_T_panel *

On entry,  PANEL  points to the data structure containing the panel information.

M       (local input)           const int

On entry,  M specifies the local number of rows of the matrix column on which this function operates.

II      (local input)           const int

On entry, II  specifies the row offset where the column to be operated on starts with respect to the panel.

JJ      (local input)           const int

On entry, JJ  specifies the column offset where the column to be operated on starts with respect to the panel.

WORK    (local workspace)       double *

On entry, WORK  is a workarray of size at least 2 * (4+2*N0). It  is assumed that  HPL_dlocmax  was called  prior  to  this routine to  initialize  the first four entries of this array. On exit, the  N0  length max row is stored in WORK[4:4+N0-1]; Note that this is also the  JJth  row  (or column) of L1. The remaining part is used as a temporary array.

See Also

HPL_dlocmax (3), HPL_dlocswpN (3), HPL_dlocswpT (3), HPL_pdpancrN (3), HPL_pdpancrT (3), HPL_pdpanllN (3), HPL_pdpanllT (3), HPL_pdpanrlN (3), HPL_pdpanrlT (3), HPL_pdrpancrN (3), HPL_pdrpancrT (3), HPL_pdrpanllN (3), HPL_pdrpanllT (3), HPL_pdrpanrlN (3), HPL_pdrpanrlT (3), HPL_pdfact (3).


October 26, 2012 HPL 2.1 HPL Library Functions