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Annotation of rpl/lapack/lapack/dlaset.f, revision 1.1

1.1     ! bertrand    1:       SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
        !             2: *
        !             3: *  -- LAPACK auxiliary routine (version 3.2) --
        !             4: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
        !             5: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
        !             6: *     November 2006
        !             7: *
        !             8: *     .. Scalar Arguments ..
        !             9:       CHARACTER          UPLO
        !            10:       INTEGER            LDA, M, N
        !            11:       DOUBLE PRECISION   ALPHA, BETA
        !            12: *     ..
        !            13: *     .. Array Arguments ..
        !            14:       DOUBLE PRECISION   A( LDA, * )
        !            15: *     ..
        !            16: *
        !            17: *  Purpose
        !            18: *  =======
        !            19: *
        !            20: *  DLASET initializes an m-by-n matrix A to BETA on the diagonal and
        !            21: *  ALPHA on the offdiagonals.
        !            22: *
        !            23: *  Arguments
        !            24: *  =========
        !            25: *
        !            26: *  UPLO    (input) CHARACTER*1
        !            27: *          Specifies the part of the matrix A to be set.
        !            28: *          = 'U':      Upper triangular part is set; the strictly lower
        !            29: *                      triangular part of A is not changed.
        !            30: *          = 'L':      Lower triangular part is set; the strictly upper
        !            31: *                      triangular part of A is not changed.
        !            32: *          Otherwise:  All of the matrix A is set.
        !            33: *
        !            34: *  M       (input) INTEGER
        !            35: *          The number of rows of the matrix A.  M >= 0.
        !            36: *
        !            37: *  N       (input) INTEGER
        !            38: *          The number of columns of the matrix A.  N >= 0.
        !            39: *
        !            40: *  ALPHA   (input) DOUBLE PRECISION
        !            41: *          The constant to which the offdiagonal elements are to be set.
        !            42: *
        !            43: *  BETA    (input) DOUBLE PRECISION
        !            44: *          The constant to which the diagonal elements are to be set.
        !            45: *
        !            46: *  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
        !            47: *          On exit, the leading m-by-n submatrix of A is set as follows:
        !            48: *
        !            49: *          if UPLO = 'U', A(i,j) = ALPHA, 1<=i<=j-1, 1<=j<=n,
        !            50: *          if UPLO = 'L', A(i,j) = ALPHA, j+1<=i<=m, 1<=j<=n,
        !            51: *          otherwise,     A(i,j) = ALPHA, 1<=i<=m, 1<=j<=n, i.ne.j,
        !            52: *
        !            53: *          and, for all UPLO, A(i,i) = BETA, 1<=i<=min(m,n).
        !            54: *
        !            55: *  LDA     (input) INTEGER
        !            56: *          The leading dimension of the array A.  LDA >= max(1,M).
        !            57: *
        !            58: * =====================================================================
        !            59: *
        !            60: *     .. Local Scalars ..
        !            61:       INTEGER            I, J
        !            62: *     ..
        !            63: *     .. External Functions ..
        !            64:       LOGICAL            LSAME
        !            65:       EXTERNAL           LSAME
        !            66: *     ..
        !            67: *     .. Intrinsic Functions ..
        !            68:       INTRINSIC          MIN
        !            69: *     ..
        !            70: *     .. Executable Statements ..
        !            71: *
        !            72:       IF( LSAME( UPLO, 'U' ) ) THEN
        !            73: *
        !            74: *        Set the strictly upper triangular or trapezoidal part of the
        !            75: *        array to ALPHA.
        !            76: *
        !            77:          DO 20 J = 2, N
        !            78:             DO 10 I = 1, MIN( J-1, M )
        !            79:                A( I, J ) = ALPHA
        !            80:    10       CONTINUE
        !            81:    20    CONTINUE
        !            82: *
        !            83:       ELSE IF( LSAME( UPLO, 'L' ) ) THEN
        !            84: *
        !            85: *        Set the strictly lower triangular or trapezoidal part of the
        !            86: *        array to ALPHA.
        !            87: *
        !            88:          DO 40 J = 1, MIN( M, N )
        !            89:             DO 30 I = J + 1, M
        !            90:                A( I, J ) = ALPHA
        !            91:    30       CONTINUE
        !            92:    40    CONTINUE
        !            93: *
        !            94:       ELSE
        !            95: *
        !            96: *        Set the leading m-by-n submatrix to ALPHA.
        !            97: *
        !            98:          DO 60 J = 1, N
        !            99:             DO 50 I = 1, M
        !           100:                A( I, J ) = ALPHA
        !           101:    50       CONTINUE
        !           102:    60    CONTINUE
        !           103:       END IF
        !           104: *
        !           105: *     Set the first min(M,N) diagonal elements to BETA.
        !           106: *
        !           107:       DO 70 I = 1, MIN( M, N )
        !           108:          A( I, I ) = BETA
        !           109:    70 CONTINUE
        !           110: *
        !           111:       RETURN
        !           112: *
        !           113: *     End of DLASET
        !           114: *
        !           115:       END