text:       SUBROUTINE PSLASE2( UPLO, M, N, ALPHA, BETA, A, IA, JA, DESCA )
  *
  *  -- ScaLAPACK auxiliary routine (version 1.7) --
  *     University of Tennessee, Knoxville, Oak Ridge National Laboratory,
  *     and University of California, Berkeley.
  *     May 1, 1997
  *
  *     .. Scalar Arguments ..
        CHARACTER          UPLO
        INTEGER            IA, JA, M, N
        REAL               ALPHA, BETA
  *     ..
  *     .. Array Arguments ..
        INTEGER            DESCA( * )
        REAL               A( * )
  *     ..
  *
  *  Purpose
  *  =======
  *
  *  PSLASE2 initializes an M-by-N distributed matrix sub( A ) denoting
  *  A(IA:IA+M-1,JA:JA+N-1) to BETA on the diagonal and ALPHA on the
  *  offdiagonals.  PSLASE2 requires that only dimension of the matrix
  *  operand is distributed.
  *
  *  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
  *  =========
  *
  *  UPLO    (global input) CHARACTER
  *          Specifies the part of the distributed matrix sub( A ) to be
  *          set:
  *          = 'U':      Upper triangular part is set; the strictly lower
  *                      triangular part of sub( A ) is not changed;
  *          = 'L':      Lower triangular part is set; the strictly upper
  *                      triangular part of sub( A ) is not changed;
  *          Otherwise:  All of the matrix sub( A ) is set.
  *
  *  M       (global input) INTEGER
  *          The number of rows to be operated on i.e the number of rows
  *          of the distributed submatrix sub( A ). M >= 0.
  *
  *  N       (global input) INTEGER
  *          The number of columns to be operated on i.e the number of
  *          columns of the distributed submatrix sub( A ). N >= 0.
  *
  *  ALPHA   (global input) REAL
  *          The constant to which the offdiagonal elements are to be
  *          set.
  *
  *  BETA    (global input) REAL
  *          The constant to which the diagonal elements are to be set.
  *
  *  A       (local output) REAL pointer into the local memory
  *          to an array of dimension (LLD_A,LOCc(JA+N-1)).  This array
  *          contains the local pieces of the distributed matrix sub( A )
  *          to be set.  On exit, the leading M-by-N submatrix sub( A )
  *          is set as follows:
  *
  *          if UPLO = 'U', A(IA+i-1,JA+j-1) = ALPHA, 1<=i<=j-1, 1<=j<=N,
  *          if UPLO = 'L', A(IA+i-1,JA+j-1) = ALPHA, j+1<=i<=M, 1<=j<=N,
  *          otherwise,     A(IA+i-1,JA+j-1) = ALPHA, 1<=i<=M, 1<=j<=N,
  *                                                   IA+i.NE.JA+j,
  *          and, for all UPLO, A(IA+i-1,JA+i-1) = BETA, 1<=i<=min(M,N).
  *
  *  IA      (global input) INTEGER
  *          The row index in the global array A indicating the first
  *          row of sub( A ).
  *
  *  JA      (global input) INTEGER
  *          The column index in the global array A indicating the
  *          first column of sub( A ).
  *
  *  DESCA   (global and local input) INTEGER array of dimension DLEN_.
  *          The array descriptor for the distributed matrix A.
  *
  *  =====================================================================
  *
  *     .. Parameters ..
        INTEGER            BLOCK_CYCLIC_2D, CSRC_, CTXT_, DLEN_, DTYPE_,
       $                   LLD_, MB_, M_, NB_, N_, RSRC_
        PARAMETER          ( BLOCK_CYCLIC_2D = 1, DLEN_ = 9, DTYPE_ = 1,
       $                     CTXT_ = 2, M_ = 3, N_ = 4, MB_ = 5, NB_ = 6,
       $                     RSRC_ = 7, CSRC_ = 8, LLD_ = 9 )
  *     ..
  *     .. Local Scalars ..
        INTEGER            HEIGHT, IACOL, IAROW, IBASE, ICOFFA, II, IIA,
       $                   IIBEG, IIEND, IINXT, ILEFT, IRIGHT, IROFFA,
       $                   ITOP, JJ, JJA, JJBEG, JJEND, JJNXT, LDA, MBA,
       $                   MP, MPA, MYCOL, MYDIST, MYROW, NBA, NPCOL,
       $                   NPROW, NQ, NQA, WIDE
  *     ..
  *     .. External Subroutines ..
        EXTERNAL           BLACS_GRIDINFO, INFOG2L, SLASET
  *     ..
  *     .. External Functions ..
        LOGICAL            LSAME
        INTEGER            ICEIL, NUMROC
        EXTERNAL           ICEIL, LSAME, NUMROC
  *     ..
  *     .. Intrinsic Functions ..
        INTRINSIC          MAX, MIN, MOD
  *     ..
  *     .. Executable Statements ..
  *
        IF( M.EQ.0 .OR. N.EQ.0 )
       $   RETURN
  *
  *     Get grid parameters
  *
        CALL BLACS_GRIDINFO( DESCA( CTXT_ ), NPROW, NPCOL, MYROW, MYCOL )
  *
        CALL INFOG2L( IA, JA, DESCA, NPROW, NPCOL, MYROW, MYCOL, IIA, JJA,
       $              IAROW, IACOL )
        MBA = DESCA( MB_ )
        NBA = DESCA( NB_ )
        LDA = DESCA( LLD_ )
        IROFFA = MOD( IA-1, MBA )
        ICOFFA = MOD( JA-1, NBA )
  *
        IF( N.LE.( NBA-ICOFFA ) ) THEN
  *
  *        It is assumed that the local columns JJA:JJA+N-1 of the matrix
  *        A are in the same process column (IACOL).
  *
  *                         N
  *                JJA             JJA+N-1
  *         /      ---------------------    \
  *   IROFFA|      |                   |    |
  *         \      |...................|    |       ( IAROW )
  *           IIA  |x                  |    | MB_A
  *                | x                 |    |
  *                |--x----------------|    /
  *                |   x               |
  *                |    x              |        ITOP
  *                |     x             |          |
  *                |      x            |      /-------\
  *                |-------x-----------|      |-------x-----------|
  *                |        x          |      |        x          |
  *                |         x         |      |         x         |
  *                |          x        |      |          x        |
  *                |           x       |      |           x       |
  *                |------------x------|      |------------x------|
  *                |             x     |      \____________/
  *                |              x    |            |
  *                |               x   |          IBASE
  *                |                x  |
  *                |-----------------x-|          Local picture
  *                |                  x|
  *                |                   |
  *                |                   |
  *                |                   |
  *                |-------------------|
  *                |                   |
  *                .                   .
  *                .                   .
  *                .      (IACOL)      .
  *
           IF( MYCOL.EQ.IACOL ) THEN
  *
              MPA = NUMROC( M+IROFFA, MBA, MYROW, IAROW, NPROW )
              IF( MPA.LE.0 )
       $         RETURN
              IF( MYROW.EQ.IAROW )
       $         MPA = MPA - IROFFA
              MYDIST = MOD( MYROW-IAROW+NPROW, NPROW )
              ITOP = MYDIST * MBA - IROFFA
  *
              IF( LSAME( UPLO, 'U' ) ) THEN
  *
                 ITOP = MAX( 0, ITOP )
                 IIBEG = IIA
                 IIEND = IIA + MPA - 1
                 IINXT = MIN( ICEIL( IIBEG, MBA ) * MBA, IIEND )
  *
     10          CONTINUE
                 IF( ( N-ITOP ).GT.0 ) THEN
                    CALL SLASET( UPLO, IINXT-IIBEG+1, N-ITOP, ALPHA, BETA,
       $                         A( IIBEG+(JJA+ITOP-1)*LDA ), LDA )
                    MYDIST = MYDIST + NPROW
                    ITOP = MYDIST * MBA - IROFFA
                    IIBEG = IINXT +1
                    IINXT = MIN( IINXT+MBA, IIEND )
                    GO TO 10
                 END IF
  *
              ELSE IF( LSAME( UPLO, 'L' ) ) THEN
  *
                 II = IIA
                 JJ = JJA
                 MP = MPA
                 IBASE = MIN( ITOP+MBA, N )
                 ITOP = MIN( MAX( 0, ITOP ), N )
  *
     20          CONTINUE
                 IF( JJ.LE.( JJA+N-1 ) ) THEN
                    HEIGHT = IBASE - ITOP
                    CALL SLASET( 'All', MP, ITOP-JJ+JJA, ALPHA, ALPHA,
       $                         A( II+(JJ-1)*LDA ), LDA )
                    CALL SLASET( UPLO, MP, HEIGHT, ALPHA, BETA,
       $                         A( II+(JJA+ITOP-1)*LDA ), LDA )
                    MP = MAX( 0, MP - HEIGHT )
                    II = II + HEIGHT
                    JJ = JJA + IBASE
                    MYDIST = MYDIST + NPROW
                    ITOP = MYDIST * MBA - IROFFA
                    IBASE = MIN( ITOP + MBA, N )
                    ITOP = MIN( ITOP, N )
                    GO TO 20
                 END IF
  *
              ELSE
  *
                 II = IIA
                 JJ = JJA
                 MP = MPA
                 IBASE = MIN( ITOP+MBA, N )
                 ITOP = MIN( MAX( 0, ITOP ), N )
  *
     30          CONTINUE
                 IF( JJ.LE.( JJA+N-1 ) ) THEN
                    HEIGHT = IBASE - ITOP
                    CALL SLASET( 'All', MPA, ITOP-JJ+JJA, ALPHA, ALPHA,
       $                         A( IIA+(JJ-1)*LDA ), LDA )
                    CALL SLASET( 'All', MPA-MP, HEIGHT, ALPHA, ALPHA,
       $                         A( IIA+(JJA+ITOP-1)*LDA ), LDA )
                    CALL SLASET( 'All', MP, HEIGHT, ALPHA, BETA,
       $                         A( II+(JJA+ITOP-1)*LDA ), LDA )
                    MP = MAX( 0, MP - HEIGHT )
                    II = II + HEIGHT
                    JJ = JJA + IBASE
                    MYDIST = MYDIST + NPROW
                    ITOP = MYDIST * MBA - IROFFA
                    IBASE = MIN( ITOP + MBA, N )
                    ITOP = MIN( ITOP, N )
                    GO TO 30
                 END IF
  *
              END IF
  *
           END IF
  *
        ELSE IF( M.LE.( MBA-IROFFA ) ) THEN
  *
  *        It is assumed that the local rows IIA:IIA+M-1 of the matrix A
  *        are in the same process row (IAROW).
  *
  *            ICOFFA
  *             / \JJA
  *        IIA  ------------------ ....            --------
  *             | .x  |    |    |                 / |    | \
  *             | . x |    |    |            ILEFT| |    | |
  *             | .  x     |    |                 | |    | |
  *             | .   x    |    |                 \ x    | |
  *             | .   |x   |    |                   |x   | | IRIGHT
  *             | .   | x  |    |                   | x  | |
  *    (IAROW)  | .   |  x |    |                   |  x | |
  *             | .   |   x|    |                   |   x| |
  *             | .   |    x    |                   |    x /
  *             | .   |    |x   |                   |    |
  *             | .   |    | x  |                   |    |
  *             | .   |    |  x |                   |    |
  *             | .   |    |   x|                   |    |
  *    IIA+M-1  ------------------ ....            -------
  *              NB_A
  *             (IACOL)                          Local picture
  *
           IF( MYROW.EQ.IAROW ) THEN
  *
              NQA = NUMROC( N+ICOFFA, NBA, MYCOL, IACOL, NPCOL )
              IF( NQA.LE.0 )
       $         RETURN
              IF( MYCOL.EQ.IACOL )
       $         NQA = NQA - ICOFFA
              MYDIST = MOD( MYCOL-IACOL+NPCOL, NPCOL )
              ILEFT = MYDIST * NBA - ICOFFA
  *
              IF( LSAME( UPLO, 'L' ) ) THEN
  *
                 ILEFT = MAX( 0, ILEFT )
                 JJBEG = JJA
                 JJEND = JJA + NQA - 1
                 JJNXT = MIN( ICEIL( JJBEG, NBA ) * NBA, JJEND )
  *
     40          CONTINUE
                 IF( ( M-ILEFT ).GT.0 ) THEN
                    CALL SLASET( UPLO, M-ILEFT, JJNXT-JJBEG+1, ALPHA,
       $                         BETA, A( IIA+ILEFT+(JJBEG-1)*LDA ), LDA )
                    MYDIST = MYDIST + NPCOL
                    ILEFT = MYDIST * NBA - ICOFFA
                    JJBEG = JJNXT +1
                    JJNXT = MIN( JJNXT+NBA, JJEND )
                    GO TO 40
                 END IF
  *
              ELSE IF( LSAME( UPLO, 'U' ) ) THEN
  *
                 II = IIA
                 JJ = JJA
                 NQ = NQA
                 IRIGHT = MIN( ILEFT+NBA, M )
                 ILEFT = MIN( MAX( 0, ILEFT ), M )
  *
     50          CONTINUE
                 IF( II.LE.( IIA+M-1 ) ) THEN
                    WIDE = IRIGHT - ILEFT
                    CALL SLASET( 'All', ILEFT-II+IIA, NQ, ALPHA, ALPHA,
       $                         A( II+(JJ-1)*LDA ), LDA )
                    CALL SLASET( UPLO, WIDE, NQ, ALPHA, BETA,
       $                         A( IIA+ILEFT+(JJ-1)*LDA ), LDA )
                    NQ = MAX( 0, NQ - WIDE )
                    II = IIA + IRIGHT
                    JJ = JJ + WIDE
                    MYDIST = MYDIST + NPCOL
                    ILEFT = MYDIST * NBA - ICOFFA
                    IRIGHT = MIN( ILEFT + NBA, M )
                    ILEFT = MIN( ILEFT, M )
                    GO TO 50
                 END IF
  *
              ELSE
  *
                 II = IIA
                 JJ = JJA
                 NQ = NQA
                 IRIGHT = MIN( ILEFT+NBA, M )
                 ILEFT = MIN( MAX( 0, ILEFT ), M )
  *
     60          CONTINUE
                 IF( II.LE.( IIA+M-1 ) ) THEN
                    WIDE = IRIGHT - ILEFT
                    CALL SLASET( 'All', ILEFT-II+IIA, NQA, ALPHA, ALPHA,
       $                         A( II+(JJA-1)*LDA ), LDA )
                    CALL SLASET( 'All', WIDE, NQA-NQ, ALPHA, ALPHA,
       $                         A( IIA+ILEFT+(JJA-1)*LDA ), LDA )
                    CALL SLASET( 'All', WIDE, NQ, ALPHA, BETA,
       $                         A( IIA+ILEFT+(JJ-1)*LDA ), LDA )
                    NQ = MAX( 0, NQ - WIDE )
                    II = IIA + IRIGHT
                    JJ = JJ + WIDE
                    MYDIST = MYDIST + NPCOL
                    ILEFT = MYDIST * NBA - ICOFFA
                    IRIGHT = MIN( ILEFT + NBA, M )
                    ILEFT = MIN( ILEFT, M )
                    GO TO 60
                 END IF
  *
              END IF
  *
           END IF
  *
        END IF
  *
        RETURN
  *
  *     End of PSLASE2
  *
        END
  