claset.f

          SUBROUTINE CLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
    *
    *  -- LAPACK auxiliary routine (version 3.1) --
    *     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
    *     November 2006
    *
    *     .. Scalar Arguments ..
          CHARACTER          UPLO
          INTEGER            LDA, M, N
          COMPLEX            ALPHA, BETA
    *     ..
    *     .. Array Arguments ..
          COMPLEX            A( LDA, * )
    *     ..
    *
    *  Purpose
    *  =======
    *
    *  CLASET initializes a 2-D array A to BETA on the diagonal and
    *  ALPHA on the offdiagonals.
    *
    *  Arguments
    *  =========
    *
    *  UPLO    (input) CHARACTER*1
    *          Specifies the part of the matrix A to be set.
    *          = 'U':      Upper triangular part is set. The lower triangle
    *                      is unchanged.
    *          = 'L':      Lower triangular part is set. The upper triangle
    *                      is unchanged.
    *          Otherwise:  All of the matrix A is set.
    *
    *  M       (input) INTEGER
    *          On entry, M specifies the number of rows of A.
    *
    *  N       (input) INTEGER
    *          On entry, N specifies the number of columns of A.
    *
    *  ALPHA   (input) COMPLEX
    *          All the offdiagonal array elements are set to ALPHA.
    *
    *  BETA    (input) COMPLEX
    *          All the diagonal array elements are set to BETA.
    *
    *  A       (input/output) COMPLEX array, dimension (LDA,N)
    *          On entry, the m by n matrix A.
    *          On exit, A(i,j) = ALPHA, 1 <= i <= m, 1 <= j <= n, i.ne.j;
    *                   A(i,i) = BETA , 1 <= i <= min(m,n)
    *
    *  LDA     (input) INTEGER
    *          The leading dimension of the array A.  LDA >= max(1,M).
    *
    *  =====================================================================
    *
    *     .. Local Scalars ..
          INTEGER            I, J
    *     ..
    *     .. External Functions ..
          LOGICAL            LSAME
          EXTERNAL           LSAME
    *     ..
    *     .. Intrinsic Functions ..
          INTRINSIC          MIN
    *     ..
    *     .. Executable Statements ..
    *
          IF( LSAME( UPLO, 'U' ) ) THEN
    *
    *        Set the diagonal to BETA and the strictly upper triangular
    *        part of the array to ALPHA.
    *
             DO 20 J = 2, N
                DO 10 I = 1, MIN( J-1, M )
                   A( I, J ) = ALPHA
       10       CONTINUE
       20    CONTINUE
             DO 30 I = 1, MIN( N, M )
                A( I, I ) = BETA
       30    CONTINUE
    *
          ELSE IF( LSAME( UPLO, 'L' ) ) THEN
    *
    *        Set the diagonal to BETA and the strictly lower triangular
    *        part of the array to ALPHA.
    *
             DO 50 J = 1, MIN( M, N )
                DO 40 I = J + 1, M
                   A( I, J ) = ALPHA
       40       CONTINUE
       50    CONTINUE
             DO 60 I = 1, MIN( N, M )
                A( I, I ) = BETA
       60    CONTINUE
    *
          ELSE
    *
    *        Set the array to BETA on the diagonal and ALPHA on the
    *        offdiagonal.
    *
             DO 80 J = 1, N
                DO 70 I = 1, M
                   A( I, J ) = ALPHA
       70       CONTINUE
       80    CONTINUE
             DO 90 I = 1, MIN( M, N )
                A( I, I ) = BETA
       90    CONTINUE
          END IF
    *
          RETURN
    *
    *     End of CLASET
    *
          END