ScaLAPACK  2.0.2
ScaLAPACK: Scalable Linear Algebra PACKage
PB_Cplascal.c File Reference
#include "../pblas.h"
#include "../PBpblas.h"
#include "../PBtools.h"
#include "../PBblacs.h"
#include "../PBblas.h"
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Functions/Subroutines

void PB_Cplascal (PBTYP_T *TYPE, char *UPLO, char *CONJUG, int M, int N, char *ALPHA, char *A, int IA, int JA, int *DESCA)

Function/Subroutine Documentation

void PB_Cplascal ( PBTYP_T *  TYPE,
char *  UPLO,
char *  CONJUG,
int  M,
int  N,
char *  ALPHA,
char *  A,
int  IA,
int  JA,
int *  DESCA 
)

Definition at line 24 of file PB_Cplascal.c.

{
/*
*  Purpose
*  =======
*
*  PB_Cplascal scales by alpha an  m by n  submatrix  sub( A )  denoting
*  A(IA:IA+M-1,JA:JA+N-1).
*
*  Notes
*  =====
*
*  A description  vector  is associated with each 2D block-cyclicly dis-
*  tributed matrix.  This  vector  stores  the  information  required to
*  establish the  mapping  between a  matrix entry and its corresponding
*  process and memory location.
*
*  In  the  following  comments,   the character _  should  be  read  as
*  "of  the  distributed  matrix".  Let  A  be a generic term for any 2D
*  block cyclicly distributed matrix.  Its description vector is DESC_A:
*
*  NOTATION         STORED IN       EXPLANATION
*  ---------------- --------------- ------------------------------------
*  DTYPE_A (global) DESCA[ DTYPE_ ] The descriptor type.
*  CTXT_A  (global) DESCA[ CTXT_  ] The BLACS context handle, indicating
*                                   the NPROW x NPCOL BLACS process grid
*                                   A  is  distributed over. The context
*                                   itself  is  global,  but  the handle
*                                   (the integer value) may vary.
*  M_A     (global) DESCA[ M_     ] The  number of rows in the distribu-
*                                   ted matrix A, M_A >= 0.
*  N_A     (global) DESCA[ N_     ] The number of columns in the distri-
*                                   buted matrix A, N_A >= 0.
*  IMB_A   (global) DESCA[ IMB_   ] The number of rows of the upper left
*                                   block of the matrix A, IMB_A > 0.
*  INB_A   (global) DESCA[ INB_   ] The  number  of columns of the upper
*                                   left   block   of   the  matrix   A,
*                                   INB_A > 0.
*  MB_A    (global) DESCA[ MB_    ] The blocking factor used to  distri-
*                                   bute the last  M_A-IMB_A  rows of A,
*                                   MB_A > 0.
*  NB_A    (global) DESCA[ NB_    ] The blocking factor used to  distri-
*                                   bute the last  N_A-INB_A  columns of
*                                   A, NB_A > 0.
*  RSRC_A  (global) DESCA[ RSRC_  ] The process row over which the first
*                                   row of the matrix  A is distributed,
*                                   NPROW > RSRC_A >= 0.
*  CSRC_A  (global) DESCA[ CSRC_  ] The  process column  over  which the
*                                   first column of  A  is  distributed.
*                                   NPCOL > CSRC_A >= 0.
*  LLD_A   (local)  DESCA[ LLD_   ] The  leading dimension  of the local
*                                   array  storing  the  local blocks of
*                                   the distributed matrix A,
*                                   IF( Lc( 1, N_A ) > 0 )
*                                      LLD_A >= MAX( 1, Lr( 1, M_A ) )
*                                   ELSE
*                                      LLD_A >= 1.
*
*  Let K be the number of  rows of a matrix A starting at the global in-
*  dex IA,i.e, A( IA:IA+K-1, : ). Lr( IA, K ) denotes the number of rows
*  that the process of row coordinate MYROW ( 0 <= MYROW < NPROW ) would
*  receive if these K rows were distributed over NPROW processes.  If  K
*  is the number of columns of a matrix  A  starting at the global index
*  JA, i.e, A( :, JA:JA+K-1, : ), Lc( JA, K ) denotes the number  of co-
*  lumns that the process MYCOL ( 0 <= MYCOL < NPCOL ) would  receive if
*  these K columns were distributed over NPCOL processes.
*
*  The values of Lr() and Lc() may be determined via a call to the func-
*  tion PB_Cnumroc:
*  Lr( IA, K ) = PB_Cnumroc( K, IA, IMB_A, MB_A, MYROW, RSRC_A, NPROW )
*  Lc( JA, K ) = PB_Cnumroc( K, JA, INB_A, NB_A, MYCOL, CSRC_A, NPCOL )
*
*  Arguments
*  =========
*
*  TYPE    (local input) pointer to a PBTYP_T structure
*          On entry,  TYPE  is a pointer to a structure of type PBTYP_T,
*          that contains type information (See pblas.h).
*
*  UPLO    (global input) pointer to CHAR
*          On entry, UPLO specifies the part  of  the submatrix sub( A )
*          to be scaled as follows:
*             = 'L' or 'l':         Lower triangular part is scaled; the
*             strictly upper triangular part of sub( A ) is not changed;
*             = 'U' or 'u':         Upper triangular part is scaled; the
*             strictly lower triangular part of sub( A ) is not changed;
*             Otherwise:  All of the submatrix sub( A ) is scaled.
*
*  CONJUG  (global input) pointer to CHAR
*          On entry,  CONJUG  specifies  what  kind of scaling should be
*          done as follows: when UPLO is 'L', 'l', 'U' or 'u' and CONJUG
*          is 'Z' or 'z', alpha is assumed to be real and the  imaginary
*          part of the diagonals are set to zero. Otherwise, alpha is of
*          the same type as the entries of sub( A ) and nothing particu-
*          lar is done to the diagonals of sub( A ).
*
*  M       (global input) INTEGER
*          On entry,  M  specifies the number of rows of  the  submatrix
*          sub( A ). M  must be at least zero.
*
*  N       (global input) INTEGER
*          On entry, N  specifies the number of columns of the submatrix
*          sub( A ). N must be at least zero.
*
*  ALPHA   (global input) pointer to CHAR
*          On entry,  ALPHA  specifies the scalar alpha, i.e., the cons-
*          tant with which the matrix elements are to be scaled.
*
*  A       (local input/local output) pointer to CHAR
*          On entry, A is an array of dimension (LLD_A, Ka), where Ka is
*          at least Lc( 1, JA+N-1 ).  Before  entry, this array contains
*          the local entries of the matrix A to be scaled.  On exit, the
*          local  entries  of this array corresponding to the to the en-
*          tries of the submatrix sub( A ) are  overwritten by the local
*          entries of the m by n scaled submatrix.
*
*  IA      (global input) INTEGER
*          On entry, IA  specifies A's global row index, which points to
*          the beginning of the submatrix sub( A ).
*
*  JA      (global input) INTEGER
*          On entry, JA  specifies A's global column index, which points
*          to the beginning of the submatrix sub( A ).
*
*  DESCA   (global and local input) INTEGER array
*          On entry, DESCA  is an integer array of dimension DLEN_. This
*          is the array descriptor for the matrix A.
*
*  -- Written on April 1, 1998 by
*     Antoine Petitet, University of Tennessee, Knoxville 37996, USA.
*
*  ---------------------------------------------------------------------
*/
/*
*  .. Local Scalars ..
*/
   char           UploA, herm, type;
   int            Acol, Arow, Aii, Aimb1, Ainb1, Ajj, Akp, Akq, Ald, Amb, Amp,
                  Amp0, Anb, Anq, Anq0, ctxt, izero=0, k, kb, ktmp, mn, mycol,
                  myrow, nb, npcol, nprow, size;
   TZSCAL_T       scal;
/*
*  .. Local Arrays ..
*/
   int            Ad0[DLEN_];
   char           * Aptr = NULL;
/* ..
*  .. Executable Statements ..
*
*/
/*
*  Quick return if possible
*/
   if( ( M <= 0 ) || ( N <= 0 ) ) return;
/*
*  If alpha is zero, then call PB_Cplapad instead.
*/
   type  = TYPE->type;
   UploA = Mupcase( UPLO[0] );
   herm  = ( UploA == CALL ? CNOCONJG : Mupcase( CONJUG[0] ) );

   if( type == SREAL )
   {
      if( ((float*)(ALPHA))[REAL_PART] == ZERO )
      {
         PB_Cplapad( TYPE, UPLO, NOCONJG, M, N, TYPE->zero, TYPE->zero, A, IA,
                     JA, DESCA );
         return;
      }
      else if( ((float*)(ALPHA))[REAL_PART] == ONE ) return;
   }
   else if( type == DREAL )
   {
      if( ((double*)(ALPHA))[REAL_PART] == ZERO )
      {
         PB_Cplapad( TYPE, UPLO, NOCONJG, M, N, TYPE->zero, TYPE->zero, A, IA,
                     JA, DESCA );
         return;
      }
      else if( ((double*)(ALPHA))[REAL_PART] == ONE ) return;
   }
   else if( type == SCPLX )
   {
      if( herm == CCONJG )
      {
         if( ((float*)(ALPHA))[REAL_PART] == ZERO )
         {
            PB_Cplapad( TYPE, UPLO, NOCONJG, M, N, TYPE->zero, TYPE->zero, A,
                        IA, JA, DESCA );
            return;
         }
      }
      else
      {
         if( ((float*)(ALPHA))[IMAG_PART] == ZERO )
         {
            if( ((float*)(ALPHA))[REAL_PART] == ZERO )
            {
               PB_Cplapad( TYPE, UPLO, NOCONJG, M, N, TYPE->zero, TYPE->zero, A,
                           IA, JA, DESCA );
               return;
            }
            else if( ((float*)(ALPHA))[REAL_PART] == ONE ) return;
         }
      }
   }
   else if( type == DCPLX )
   {
      if( herm == CCONJG )
      {
         if( ((double*)(ALPHA))[REAL_PART] == ZERO )
         {
            PB_Cplapad( TYPE, UPLO, NOCONJG, M, N, TYPE->zero, TYPE->zero, A,
                        IA, JA, DESCA );
            return;
         }
      }
      else
      {
         if( ((double*)(ALPHA))[IMAG_PART] == ZERO )
         {
            if( ((double*)(ALPHA))[REAL_PART] == ZERO )
            {
               PB_Cplapad( TYPE, UPLO, NOCONJG, M, N, TYPE->zero, TYPE->zero, A,
                           IA, JA, DESCA );
               return;
            }
            else if( ((double*)(ALPHA))[REAL_PART] == ONE ) return;
         }
      }
   }
/*
*  Retrieve process grid information
*/
   Cblacs_gridinfo( ( ctxt = DESCA[CTXT_] ), &nprow, &npcol, &myrow, &mycol );
/*
*  Compute descriptor Ad0 for sub( A )
*/
   PB_Cdescribe( M, N, IA, JA, DESCA, nprow, npcol, myrow, mycol, &Aii, &Ajj,
                 &Ald, &Aimb1, &Ainb1, &Amb, &Anb, &Arow, &Acol, Ad0 );
/*
*  Quick return if I don't own any of sub( A ).
*/
   Amp  = PB_Cnumroc( M, 0, Aimb1, Amb, myrow, Arow, nprow );
   Anq  = PB_Cnumroc( N, 0, Ainb1, Anb, mycol, Acol, npcol );
   if( ( Amp <= 0 ) || ( Anq <= 0 ) ) return;

   size = TYPE->size;
   scal = ( herm == CCONJG ? TYPE->Fhescal : TYPE->Ftzscal );
   Aptr = Mptr( A, Aii, Ajj, Ald, size );
/*
*  When the entire sub( A ) needs to be scaled or when sub( A ) is replicated in
*  all processes, just call the local routine.
*/
   if( ( Mupcase( UPLO[0] ) == CALL ) ||
       ( ( ( Arow < 0 ) || ( nprow == 1 ) ) &&
         ( ( Acol < 0 ) || ( npcol == 1 ) ) ) )
   {
      scal( C2F_CHAR( UPLO ), &Amp, &Anq, &izero, ALPHA, Aptr, &Ald );
      return;
   }
/*
*  Computational partitioning size is computed as the product of the logical
*  value returned by pilaenv_ and two times the least common multiple of nprow
*  and npcol.
*/
   nb = 2 * pilaenv_( &ctxt, C2F_CHAR( &type ) ) *
        PB_Clcm( ( Arow >= 0 ? nprow : 1 ), ( Acol >= 0 ? npcol : 1 ) );

   mn = MIN( M, N );

   if( Mupcase( UPLO[0] ) == CLOWER )
   {
/*
*  Lower triangle of sub( A ): proceed by block of columns. For each block of
*  columns, operate on the logical diagonal block first and then the remaining
*  rows of that block of columns.
*/
      for( k = 0; k < mn; k += nb )
      {
         kb   = mn - k; ktmp = k + ( kb = MIN( kb, nb ) );
         PB_Cplasca2( TYPE, UPLO, CONJUG, kb, kb, ALPHA, Aptr, k, k, Ad0 );
         Akp  = PB_Cnumroc( ktmp, 0, Aimb1, Amb, myrow, Arow, nprow );
         Akq  = PB_Cnumroc( k,    0, Ainb1, Anb, mycol, Acol, npcol );
         Anq0 = PB_Cnumroc( kb,   k, Ainb1, Anb, mycol, Acol, npcol );
         if( ( Amp0 = Amp - Akp ) > 0 )
            scal( C2F_CHAR( ALL ), &Amp0, &Anq0, &izero, ALPHA, Mptr( Aptr,
                  Akp, Akq, Ald, size ), &Ald );
      }
   }
   else if( Mupcase( UPLO[0] ) == CUPPER )
   {
/*
*  Upper triangle of sub( A ): proceed by block of columns. For each block of
*  columns, operate on the trailing rows and then the logical diagonal block
*  of that block of columns. When M < N, the last columns of sub( A ) are
*  handled together.
*/
      for( k = 0; k < mn; k += nb )
      {
         kb   = mn - k; kb = MIN( kb, nb );
         Akp  = PB_Cnumroc( k,  0, Aimb1, Amb, myrow, Arow, nprow );
         Akq  = PB_Cnumroc( k,  0, Ainb1, Anb, mycol, Acol, npcol );
         Anq0 = PB_Cnumroc( kb, k, Ainb1, Anb, mycol, Acol, npcol );
         if( Akp > 0 )
            scal( C2F_CHAR( ALL ), &Akp, &Anq0, &izero, ALPHA, Mptr( Aptr,
                  0, Akq, Ald, size ), &Ald );
         PB_Cplasca2( TYPE, UPLO, CONJUG, kb, kb, ALPHA, Aptr, k, k, Ad0 );
      }
      if( ( Anq -= ( Akq += Anq0 ) ) > 0 )
         scal( C2F_CHAR( ALL ), &Amp, &Anq, &izero, ALPHA, Mptr( Aptr, 0,
               Akq, Ald, size ), &Ald );
   }
   else
   {
/*
*  All of sub( A ): proceed by block of columns. For each block of columns,
*  operate on the trailing rows, then the logical diagonal block, and finally
*  the remaining rows of that block of columns. When M < N, the last columns
*  of sub( A ) are handled together.
*/
      for( k = 0; k < mn; k += nb )
      {
         kb   = mn - k; kb = MIN( kb, nb );
         Akp  = PB_Cnumroc( k,  0, Aimb1, Amb, myrow, Arow, nprow );
         Akq  = PB_Cnumroc( k,  0, Ainb1, Anb, mycol, Acol, npcol );
         Anq0 = PB_Cnumroc( kb, k, Ainb1, Anb, mycol, Acol, npcol );
         if( Akp > 0 )
            scal( C2F_CHAR( ALL ), &Akp, &Anq0, &izero, ALPHA, Mptr( Aptr,
                  0, Akq, Ald, size ), &Ald );
         PB_Cplasca2( TYPE, UPLO, NOCONJG, kb, kb, ALPHA, Aptr, k, k, Ad0 );
         Akp = PB_Cnumroc( k+kb, 0, Aimb1, Amb, myrow, Arow, nprow );
         if( ( Amp0 = Amp - Akp ) > 0 )
            scal( C2F_CHAR( ALL ), &Amp0, &Anq0, &izero, ALPHA, Mptr( Aptr,
                  Akp, Akq, Ald, size ), &Ald );
      }
      if( ( Anq -= ( Akq += Anq0 ) ) > 0 )
         scal( C2F_CHAR( ALL ), &Amp, &Anq, &izero, ALPHA, Mptr( Aptr, 0,
               Akq, Ald, size ), &Ald );
   }
/*
*  End of PB_Cplascal
*/
}

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