PDLAWIL(3)    ScaLAPACK routine of NEC Numeric Library Collection   PDLAWIL(3)



NAME
       PDLAWIL  - get the transform given by H44,H33, & H43H34 into V starting
       at row M

SYNOPSIS
       SUBROUTINE PDLAWIL( II, JJ, M, A, DESCA, H44, H33, H43H34, V )

           INTEGER         II, JJ, M

           DOUBLE          PRECISION H33, H43H34, H44

           INTEGER         DESCA( * )

           DOUBLE          PRECISION A( * ), V( * )

PURPOSE
       PDLAWIL gets the transform given by H44,H33, & H43H34 into  V  starting
       at row M.

       Notes
       =====

       Each  global data object is described by an associated description vec-
       tor.  This vector stores the information required to establish the map-
       ping between an object element and its corresponding process and memory
       location.

       Let A be a generic term for any 2D block  cyclicly  distributed  array.
       Such a global array has an associated description vector DESCA.  In the
       following comments, the character _ should be read as  "of  the  global
       array".

       NOTATION        STORED IN      EXPLANATION
       --------------- -------------- --------------------------------------
       DTYPE_A(global) DESCA( DTYPE_ )The descriptor type.  In this case,
                                      DTYPE_A = 1.
       CTXT_A (global) DESCA( CTXT_ ) The BLACS context handle, indicating
                                      the BLACS process grid A is distribu-
                                      ted over. The context itself is glo-
                                      bal, but the handle (the integer
                                      value) may vary.
       M_A    (global) DESCA( M_ )    The number of rows in the global
                                      array A.
       N_A    (global) DESCA( N_ )    The number of columns in the global
                                      array A.
       MB_A   (global) DESCA( MB_ )   The blocking factor used to distribute
                                      the rows of the array.
       NB_A   (global) DESCA( NB_ )   The blocking factor used to distribute
                                      the columns of the array.
       RSRC_A (global) DESCA( RSRC_ ) The process row over which the first
                                      row  of  the  array  A  is  distributed.
       CSRC_A (global) DESCA( CSRC_ ) The process column over which the
                                      first column of the array A is
                                      distributed.
       LLD_A  (local)  DESCA( LLD_ )  The leading dimension of the local
                                      array.  LLD_A >= MAX(1,LOCr(M_A)).

       Let K be the number of rows or columns of  a  distributed  matrix,  and
       assume that its process grid has dimension p x q.
       LOCr(  K  )  denotes  the  number of elements of K that a process would
       receive if K were distributed over the p processes of its process  col-
       umn.
       Similarly, LOCc( K ) denotes the number of elements of K that a process
       would receive if K were distributed over the q processes of its process
       row.
       The  values  of  LOCr()  and LOCc() may be determined via a call to the
       ScaLAPACK tool function, NUMROC:
               LOCr( M ) = NUMROC( M, MB_A, MYROW, RSRC_A, NPROW ),
               LOCc( N ) = NUMROC( N, NB_A, MYCOL, CSRC_A, NPCOL ).  An  upper
       bound for these quantities may be computed by:
               LOCr( M ) <= ceil( ceil(M/MB_A)/NPROW )*MB_A
               LOCc( N ) <= ceil( ceil(N/NB_A)/NPCOL )*NB_A


ARGUMENTS
       II      (global input) INTEGER
               Row owner of H(M+2,M+2)

       JJ      (global input) INTEGER
               Column owner of H(M+2,M+2)

       M       (global input) INTEGER
               On   entry,  this  is  where  the  transform  starts  (row  M.)
               Unchanged on exit.

       A       (global input) DOUBLE PRECISION array, dimension
               (DESCA(LLD_),*) On entry, the Hessenberg matrix.  Unchanged  on
               exit.

       DESCA   (global and local input) INTEGER array of dimension DLEN_.
               The  array  descriptor for the distributed matrix A.  Unchanged
               on exit.

               H44 H33 H43H34  (global input)  DOUBLE  PRECISION  These  three
               values  are  for  the  double shift QR iteration.  Unchanged on
               exit.

       V       (global output) DOUBLE PRECISION array of size 3.
               Contains the transform on ouput.

               Implemented by:  G. Henry, November 17, 1996



ScaLAPACK routine               31 October 2017                     PDLAWIL(3)