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    1: *> \brief \b DLASET initializes the off-diagonal elements and the diagonal elements of a matrix to given values.
    2: *
    3: *  =========== DOCUMENTATION ===========
    4: *
    5: * Online html documentation available at
    6: *            http://www.netlib.org/lapack/explore-html/
    7: *
    8: *> \htmlonly
    9: *> Download DLASET + dependencies
   10: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlaset.f">
   11: *> [TGZ]</a>
   12: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlaset.f">
   13: *> [ZIP]</a>
   14: *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlaset.f">
   15: *> [TXT]</a>
   16: *> \endhtmlonly
   17: *
   18: *  Definition:
   19: *  ===========
   20: *
   21: *       SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
   22: *
   23: *       .. Scalar Arguments ..
   24: *       CHARACTER          UPLO
   25: *       INTEGER            LDA, M, N
   26: *       DOUBLE PRECISION   ALPHA, BETA
   27: *       ..
   28: *       .. Array Arguments ..
   29: *       DOUBLE PRECISION   A( LDA, * )
   30: *       ..
   31: *
   32: *
   33: *> \par Purpose:
   34: *  =============
   35: *>
   36: *> \verbatim
   37: *>
   38: *> DLASET initializes an m-by-n matrix A to BETA on the diagonal and
   39: *> ALPHA on the offdiagonals.
   40: *> \endverbatim
   41: *
   42: *  Arguments:
   43: *  ==========
   44: *
   45: *> \param[in] UPLO
   46: *> \verbatim
   47: *>          UPLO is CHARACTER*1
   48: *>          Specifies the part of the matrix A to be set.
   49: *>          = 'U':      Upper triangular part is set; the strictly lower
   50: *>                      triangular part of A is not changed.
   51: *>          = 'L':      Lower triangular part is set; the strictly upper
   52: *>                      triangular part of A is not changed.
   53: *>          Otherwise:  All of the matrix A is set.
   54: *> \endverbatim
   55: *>
   56: *> \param[in] M
   57: *> \verbatim
   58: *>          M is INTEGER
   59: *>          The number of rows of the matrix A.  M >= 0.
   60: *> \endverbatim
   61: *>
   62: *> \param[in] N
   63: *> \verbatim
   64: *>          N is INTEGER
   65: *>          The number of columns of the matrix A.  N >= 0.
   66: *> \endverbatim
   67: *>
   68: *> \param[in] ALPHA
   69: *> \verbatim
   70: *>          ALPHA is DOUBLE PRECISION
   71: *>          The constant to which the offdiagonal elements are to be set.
   72: *> \endverbatim
   73: *>
   74: *> \param[in] BETA
   75: *> \verbatim
   76: *>          BETA is DOUBLE PRECISION
   77: *>          The constant to which the diagonal elements are to be set.
   78: *> \endverbatim
   79: *>
   80: *> \param[out] A
   81: *> \verbatim
   82: *>          A is DOUBLE PRECISION array, dimension (LDA,N)
   83: *>          On exit, the leading m-by-n submatrix of A is set as follows:
   84: *>
   85: *>          if UPLO = 'U', A(i,j) = ALPHA, 1<=i<=j-1, 1<=j<=n,
   86: *>          if UPLO = 'L', A(i,j) = ALPHA, j+1<=i<=m, 1<=j<=n,
   87: *>          otherwise,     A(i,j) = ALPHA, 1<=i<=m, 1<=j<=n, i.ne.j,
   88: *>
   89: *>          and, for all UPLO, A(i,i) = BETA, 1<=i<=min(m,n).
   90: *> \endverbatim
   91: *>
   92: *> \param[in] LDA
   93: *> \verbatim
   94: *>          LDA is INTEGER
   95: *>          The leading dimension of the array A.  LDA >= max(1,M).
   96: *> \endverbatim
   97: *
   98: *  Authors:
   99: *  ========
  100: *
  101: *> \author Univ. of Tennessee
  102: *> \author Univ. of California Berkeley
  103: *> \author Univ. of Colorado Denver
  104: *> \author NAG Ltd.
  105: *
  106: *> \date December 2016
  107: *
  108: *> \ingroup OTHERauxiliary
  109: *
  110: *  =====================================================================
  111:       SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
  112: *
  113: *  -- LAPACK auxiliary routine (version 3.7.0) --
  114: *  -- LAPACK is a software package provided by Univ. of Tennessee,    --
  115: *  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
  116: *     December 2016
  117: *
  118: *     .. Scalar Arguments ..
  119:       CHARACTER          UPLO
  120:       INTEGER            LDA, M, N
  121:       DOUBLE PRECISION   ALPHA, BETA
  122: *     ..
  123: *     .. Array Arguments ..
  124:       DOUBLE PRECISION   A( LDA, * )
  125: *     ..
  126: *
  127: * =====================================================================
  128: *
  129: *     .. Local Scalars ..
  130:       INTEGER            I, J
  131: *     ..
  132: *     .. External Functions ..
  133:       LOGICAL            LSAME
  134:       EXTERNAL           LSAME
  135: *     ..
  136: *     .. Intrinsic Functions ..
  137:       INTRINSIC          MIN
  138: *     ..
  139: *     .. Executable Statements ..
  140: *
  141:       IF( LSAME( UPLO, 'U' ) ) THEN
  142: *
  143: *        Set the strictly upper triangular or trapezoidal part of the
  144: *        array to ALPHA.
  145: *
  146:          DO 20 J = 2, N
  147:             DO 10 I = 1, MIN( J-1, M )
  148:                A( I, J ) = ALPHA
  149:    10       CONTINUE
  150:    20    CONTINUE
  151: *
  152:       ELSE IF( LSAME( UPLO, 'L' ) ) THEN
  153: *
  154: *        Set the strictly lower triangular or trapezoidal part of the
  155: *        array to ALPHA.
  156: *
  157:          DO 40 J = 1, MIN( M, N )
  158:             DO 30 I = J + 1, M
  159:                A( I, J ) = ALPHA
  160:    30       CONTINUE
  161:    40    CONTINUE
  162: *
  163:       ELSE
  164: *
  165: *        Set the leading m-by-n submatrix to ALPHA.
  166: *
  167:          DO 60 J = 1, N
  168:             DO 50 I = 1, M
  169:                A( I, J ) = ALPHA
  170:    50       CONTINUE
  171:    60    CONTINUE
  172:       END IF
  173: *
  174: *     Set the first min(M,N) diagonal elements to BETA.
  175: *
  176:       DO 70 I = 1, MIN( M, N )
  177:          A( I, I ) = BETA
  178:    70 CONTINUE
  179: *
  180:       RETURN
  181: *
  182: *     End of DLASET
  183: *
  184:       END