PSLAWIL(l)						   LAPACK routine (version 1.5 )						PSLAWIL(l)

NAME

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

SYNOPSIS

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

	   INTEGER	   II, JJ, M

	   REAL 	   H33, H43H34, H44

	   INTEGER	   DESCA( * )

	   REAL 	   A( * ), V( * )

PURPOSE

       PSLAWIL 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 vector.  This vector stores the information required to establish the
       mapping 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) REAL 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) REAL These three values are for the double shift QR iteration.  Unchanged on exit.

       V       (global output) REAL array of size 3.
	       Contains the transform on output.

	       Implemented by:	G. Henry, November 17, 1996

LAPACK version 1.5						    12 May 1997 							PSLAWIL(l)