dlaset.F90 Source File


Source Code

#include "ESMF_LapackBlas.inc"
!> \brief \b DLASET
!
!  =========== DOCUMENTATION ===========
!
! Online html documentation available at
!            http://www.netlib.org/lapack/explore-html/
!
!> \htmlonly
!> Download DLASET + dependencies
!> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlaset.f">
!> [TGZ]</a>
!> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlaset.f">
!> [ZIP]</a>
!> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlaset.f">
!> [TXT]</a>
!> \endhtmlonly
!
!  Definition:
!  ===========
!
!       SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
!
!       .. Scalar Arguments ..
!       CHARACTER          UPLO
!       INTEGER            LDA, M, N
!       DOUBLE PRECISION   ALPHA, BETA
!       ..
!       .. Array Arguments ..
!       DOUBLE PRECISION   A( LDA, * )
!       ..
!
!
!> \par Purpose:
!  =============
!>
!> \verbatim
!>
!> DLASET initializes an m-by-n matrix A to BETA on the diagonal and
!> ALPHA on the offdiagonals.
!> \endverbatim
!
!  Arguments:
!  ==========
!
!> \param[in] UPLO
!> \verbatim
!>          UPLO is CHARACTER*1
!>          Specifies the part of the matrix A to be set.
!>          = 'U':      Upper triangular part is set; the strictly lower
!>                      triangular part of A is not changed.
!>          = 'L':      Lower triangular part is set; the strictly upper
!>                      triangular part of A is not changed.
!>          Otherwise:  All of the matrix A is set.
!> \endverbatim
!>
!> \param[in] M
!> \verbatim
!>          M is INTEGER
!>          The number of rows of the matrix A.  M >= 0.
!> \endverbatim
!>
!> \param[in] N
!> \verbatim
!>          N is INTEGER
!>          The number of columns of the matrix A.  N >= 0.
!> \endverbatim
!>
!> \param[in] ALPHA
!> \verbatim
!>          ALPHA is DOUBLE PRECISION
!>          The constant to which the offdiagonal elements are to be set.
!> \endverbatim
!>
!> \param[in] BETA
!> \verbatim
!>          BETA is DOUBLE PRECISION
!>          The constant to which the diagonal elements are to be set.
!> \endverbatim
!>
!> \param[in,out] A
!> \verbatim
!>          A is DOUBLE PRECISION array, dimension (LDA,N)
!>          On exit, the leading m-by-n submatrix of A is set as follows:
!>
!>          if UPLO = 'U', A(i,j) = ALPHA, 1<=i<=j-1, 1<=j<=n,
!>          if UPLO = 'L', A(i,j) = ALPHA, j+1<=i<=m, 1<=j<=n,
!>          otherwise,     A(i,j) = ALPHA, 1<=i<=m, 1<=j<=n, i.ne.j,
!>
!>          and, for all UPLO, A(i,i) = BETA, 1<=i<=min(m,n).
!> \endverbatim
!>
!> \param[in] LDA
!> \verbatim
!>          LDA is INTEGER
!>          The leading dimension of the array A.  LDA >= max(1,M).
!> \endverbatim
!
!  Authors:
!  ========
!
!> \author Univ. of Tennessee
!> \author Univ. of California Berkeley
!> \author Univ. of Colorado Denver
!> \author NAG Ltd.
!
!> \date November 2011
!
!> \ingroup auxOTHERauxiliary
!
!  =====================================================================
      SUBROUTINE DLASET( UPLO, M, N, ALPHA, BETA, A, LDA )
!
!  -- LAPACK auxiliary routine (version 3.4.0) --
!  -- LAPACK is a software package provided by Univ. of Tennessee,    --
!  -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
!     November 2011
!
!     .. Scalar Arguments ..
      CHARACTER          UPLO
      INTEGER            LDA, M, N
      DOUBLE PRECISION   ALPHA, BETA
!     ..
!     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * )
!     ..
!
! =====================================================================
!
!     .. Local Scalars ..
      INTEGER            I, J
!     ..
!     .. External Functions ..
      LOGICAL            LSAME
      EXTERNAL           LSAME
!     ..
!     .. Intrinsic Functions ..
      INTRINSIC          MIN
!     ..
!     .. Executable Statements ..
!
      IF( LSAME( UPLO, 'U' ) ) THEN
!
!        Set the strictly upper triangular or trapezoidal 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
!
      ELSE IF( LSAME( UPLO, 'L' ) ) THEN
!
!        Set the strictly lower triangular or trapezoidal part of the
!        array to ALPHA.
!
         DO 40 J = 1, MIN( M, N )
            DO 30 I = J + 1, M
               A( I, J ) = ALPHA
   30       CONTINUE
   40    CONTINUE
!
      ELSE
!
!        Set the leading m-by-n submatrix to ALPHA.
!
         DO 60 J = 1, N
            DO 50 I = 1, M
               A( I, J ) = ALPHA
   50       CONTINUE
   60    CONTINUE
      END IF
!
!     Set the first min(M,N) diagonal elements to BETA.
!
      DO 70 I = 1, MIN( M, N )
         A( I, I ) = BETA
   70 CONTINUE
!
      RETURN
!
!     End of DLASET
!
      END