SUBROUTINE PSFILLPAD( ICTXT, M, N, A, LDA, IPRE, IPOST, CHKVAL ) *
* -- ScaLAPACK tools routine (version 1.5) --

*     University of Tennessee, Knoxville, Oak Ridge National Laboratory,
*     and University of California, Berkeley.
*     May 1, 1997
*
*     .. Scalar Arguments ..
      INTEGER            ICTXT, IPOST, IPRE, LDA, M, N
      REAL               CHKVAL
*     ..
*     .. Array Arguments ..
      REAL               A( * )
*     ..

*
* Purpose


*
* PSFILLPAD surrounds a two dimensional local array with a guard- * zone initialized to the value CHKVAL. The user may later call the * routine PSCHEKPAD to discover if the guardzone has been * violated. There are three guardzones. The first is a buffer of size * IPRE that is before the start of the array. The second is the buffer * of size IPOST which is after the end of the array to be padded. * Finally, there is a guard zone inside every column of the array to * be padded, in the elements of A(M+1:LDA, J). *
* Arguments
*
* ICTXT (global input) INTEGER
*          The BLACS context handle, indicating the global context of
*          the operation. The context itself is global.
*
*  M       (local input) INTEGER
*          The number of rows in the local array.
*
*  N       (local input) INTEGER
*          The number of columns in the local array.
*
*  A       (local input/local output) REAL, array of
*          dimension (LDA,N). A location IPRE elements in front of
*          the matrix to be padded.
*
*  LDA     (local input) INTEGER
*          The leading Dimension of the local array to be padded.

*
* IPRE (local input) INTEGER

*          The size of the guard zone to put before the start of
*          padded array.

*
* IPOST (local input) INTEGER
* The size of the guard zone to put after padded array. *
* CHKVAL (local input) REAL
* The value to pad matrix with. *


*
*     .. Local Scalars ..
      INTEGER            I, J, K
*     ..
*     .. Executable Statements ..
*
*     Put check buffer in front of A
*
      IF( IPRE.GT.0 ) THEN
         DO 10 I = 1, IPRE
            A( I ) = CHKVAL
   10    CONTINUE
      ELSE
         WRITE( *, FMT = * ) 'WARNING no pre-guardzone in PSFILLPAD'
      END IF
*
*     Put check buffer in back of A
*
      IF( IPOST.GT.0 ) THEN
         J = IPRE+LDA*N+1
         DO 20 I = J, J+IPOST-1
            A( I ) = CHKVAL
   20    CONTINUE
      ELSE
         WRITE( *, FMT = * ) 'WARNING no post-guardzone in PSFILLPAD'
      END IF
*
*     Put check buffer in all (LDA-M) gaps
*
      IF( LDA.GT.M ) THEN
         K = IPRE + M + 1
         DO 40 J = 1, N
            DO 30 I = K, K + (LDA-M) - 1
               A( I ) = CHKVAL
   30       CONTINUE
            K = K + LDA
   40    CONTINUE
      END IF
*
      RETURN
*
*     End of PSFILLPAD
*
      END