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PCLAEVSWP(l)                           )                          PCLAEVSWP(l)


NAME

       PCLAEVSWP - 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 PCLAEVSWP( N, ZIN, LDZI, Z, IZ, JZ, DESCZ, NVS, KEY, RWORK,
                             LRWORK )
           INTEGER IZ, JZ, LDZI, LRWORK, N
           INTEGER DESCZ( * ), KEY( * ), NVS( * )
           REAL RWORK( * ), ZIN( LDZI, * )
           COMPLEX Z( * )


PURPOSE

       PCLAEVSWP 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) COMPLEX 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.

       RWORK    (local workspace) REAL array, dimension (LRWORK)

       LRWORK   (local input) INTEGER dimension of RWORK

ScaLAPACK version 1.7           13 August 2001                    PCLAEVSWP(l)

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