NAME

       PZDRSCL  -  multiplie  an N-element complex distributed vector sub( X ) by the real scalar
       1/a

SYNOPSIS

       SUBROUTINE PZDRSCL( N, SA, SX, IX, JX, DESCX, INCX )

           INTEGER         IX, INCX, JX, N

           DOUBLE          PRECISION SA

           INTEGER         DESCX( * )

           COMPLEX*16      SX( * )

PURPOSE

       PZDRSCL multiplies an N-element complex distributed vector sub( X )  by  the  real  scalar
       1/a.  This  is done without overflow or underflow as long as the final sub( X )/a does not
       overflow or underflow.

       where sub( X ) denotes X(IX:IX+N-1,JX:JX), if INCX = 1,
                              X(IX:IX,JX:JX+N-1), if INCX = M_X.

       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
       ---------------  --------------  --------------------------------------  DT_A     (global)
       descA[ DT_ ]   The descriptor type.  In this case,
                                      DT_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 distribu-
                                      te the rows of the array.
       NB_A   (global) descA[ NB_ ]   The blocking factor used to distribu-
                                      te  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 column.
       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

       Because vectors may be seen as particular matrices, a distributed vector is considered  to
       be a distributed matrix.

ARGUMENTS

       N       (global input) pointer to INTEGER
               The number of components of the distributed vector sub( X ).  N >= 0.

       SA      (global input) DOUBLE PRECISION
               The scalar a which is used to divide each component of sub( X ).  SA must be >= 0,
               or the subroutine will divide by zero.

       SX      (local input/local output) COMPLEX*16 array
               containing the local pieces of a distributed matrix of dimension  of  at  least  (
               (JX-1)*M_X  +  IX + ( N - 1 )*abs( INCX ) ) This array contains the entries of the
               distributed vector sub( X ).

       IX      (global input) pointer to INTEGER
               The global row index of the submatrix of the distributed matrix X to operate on.

       JX      (global input) pointer to INTEGER
               The global column index of the submatrix of the distributed matrix  X  to  operate
               on.

       DESCX   (global and local input) INTEGER array of dimension 8.
               The array descriptor of the distributed matrix X.

       INCX    (global input) pointer to INTEGER
               The  global increment for the elements of X. Only two values of INCX are supported
               in this version, namely 1 and M_X.