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NAME

       PSLAEVSWP  -  move  the  eigenvectors (potentially unsorted) from where
       they are computed, to a ScaLAPACK standard block cyclic  array,  sorted
       so that the corresponding eigenvalues are sorted

SYNOPSIS

       SUBROUTINE PSLAEVSWP( N,  ZIN,  LDZI, Z, IZ, JZ, DESCZ, NVS, KEY, WORK,
                             LWORK )

           INTEGER           IZ, JZ, LDZI, LWORK, N

           INTEGER           DESCZ( * ), KEY( * ), NVS( * )

           REAL              WORK( * ), Z( * ), ZIN( LDZI, * )

PURPOSE

       PSLAEVSWP moves the eigenvectors (potentially unsorted) from where they
       are  computed,  to  a  ScaLAPACK standard block cyclic array, sorted so
       that the corresponding eigenvalues are sorted.

       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
       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

ARGUMENTS

       NP  =  the number of rows local to a given process.  NQ = the number of
       columns local to a given process.

       N       (global input) INTEGER
               The order of the matrix A.  N >= 0.

       ZIN     (local input) REAL array,
               dimension ( LDZI, NVS(iam) ) The eigenvectors on  input.   Each
               eigenvector  resides  entirely  in  one  process.  Each process
               holds a contiguous set of  NVS(iam)  eigenvectors.   The  first
               eigenvector which the process holds is:  sum for i=[0,iam-1) of
               NVS(i)

       LDZI    (locl input) INTEGER
               leading dimension of the ZIN array

       Z       (local output) REAL array
               global dimension (N, N), local dimension (DESCZ(DLEN_), NQ) The
               eigenvectors  on output.  The eigenvectors are distributed in a
               block cyclic manner in both dimensions, with a  block  size  of
               NB.

       IZ      (global input) INTEGER
               Z’s  global  row  index,  which  points to the beginning of the
               submatrix which is to be operated on.

       JZ      (global input) INTEGER
               Z’s global column index, which points to the beginning  of  the
               submatrix which is to be operated on.

       DESCZ   (global and local input) INTEGER array of dimension DLEN_.
               The array descriptor for the distributed matrix Z.

       NVS     (global input) INTEGER array, dimension( nprocs+1 )
               nvs(i)  =  number  of  processes number of eigenvectors held by
               processes [0,i-1) nvs(1) = number  of  eigen  vectors  held  by
               [0,1-1)  ==  0  nvs(nprocs+1) = number of eigen vectors held by
               [0,nprocs) == total number of eigenvectors

       KEY     (global input) INTEGER array, dimension( N )
               Indicates the actual index (after  sorting)  for  each  of  the
               eigenvectors.

       WORK    (local workspace) REAL array, dimension (LWORK)

       LWORK   (local input) INTEGER dimension of WORK