dlascl.F90 Source File


Source Code

#include "ESMF_LapackBlas.inc"
!> \brief \b DLASCL
!
!  =========== DOCUMENTATION ===========
!
! Online html documentation available at
!            http://www.netlib.org/lapack/explore-html/
!
!> \htmlonly
!> Download DLASCL + dependencies
!> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/dlascl.f">
!> [TGZ]</a>
!> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/dlascl.f">
!> [ZIP]</a>
!> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/dlascl.f">
!> [TXT]</a>
!> \endhtmlonly
!
!  Definition:
!  ===========
!
!       SUBROUTINE DLASCL( TYPE, KL, KU, CFROM, CTO, M, N, A, LDA, INFO )
!
!       .. Scalar Arguments ..
!       CHARACTER          TYPE
!       INTEGER            INFO, KL, KU, LDA, M, N
!       DOUBLE PRECISION   CFROM, CTO
!       ..
!       .. Array Arguments ..
!       DOUBLE PRECISION   A( LDA, * )
!       ..
!
!
!> \par Purpose:
!  =============
!>
!> \verbatim
!>
!> DLASCL multiplies the M by N real matrix A by the real scalar
!> CTO/CFROM.  This is done without over/underflow as long as the final
!> result CTO*A(I,J)/CFROM does not over/underflow. TYPE specifies that
!> A may be full, upper triangular, lower triangular, upper Hessenberg,
!> or banded.
!> \endverbatim
!
!  Arguments:
!  ==========
!
!> \param[in] TYPE
!> \verbatim
!>          TYPE is CHARACTER*1
!>          TYPE indices the storage type of the input matrix.
!>          = 'G':  A is a full matrix.
!>          = 'L':  A is a lower triangular matrix.
!>          = 'U':  A is an upper triangular matrix.
!>          = 'H':  A is an upper Hessenberg matrix.
!>          = 'B':  A is a symmetric band matrix with lower bandwidth KL
!>                  and upper bandwidth KU and with the only the lower
!>                  half stored.
!>          = 'Q':  A is a symmetric band matrix with lower bandwidth KL
!>                  and upper bandwidth KU and with the only the upper
!>                  half stored.
!>          = 'Z':  A is a band matrix with lower bandwidth KL and upper
!>                  bandwidth KU. See DGBTRF for storage details.
!> \endverbatim
!>
!> \param[in] KL
!> \verbatim
!>          KL is INTEGER
!>          The lower bandwidth of A.  Referenced only if TYPE = 'B',
!>          'Q' or 'Z'.
!> \endverbatim
!>
!> \param[in] KU
!> \verbatim
!>          KU is INTEGER
!>          The upper bandwidth of A.  Referenced only if TYPE = 'B',
!>          'Q' or 'Z'.
!> \endverbatim
!>
!> \param[in] CFROM
!> \verbatim
!>          CFROM is DOUBLE PRECISION
!> \endverbatim
!>
!> \param[in] CTO
!> \verbatim
!>          CTO is DOUBLE PRECISION
!>
!>          The matrix A is multiplied by CTO/CFROM. A(I,J) is computed
!>          without over/underflow if the final result CTO*A(I,J)/CFROM
!>          can be represented without over/underflow.  CFROM must be
!>          nonzero.
!> \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,out] A
!> \verbatim
!>          A is DOUBLE PRECISION array, dimension (LDA,N)
!>          The matrix to be multiplied by CTO/CFROM.  See TYPE for the
!>          storage type.
!> \endverbatim
!>
!> \param[in] LDA
!> \verbatim
!>          LDA is INTEGER
!>          The leading dimension of the array A.  LDA >= max(1,M).
!> \endverbatim
!>
!> \param[out] INFO
!> \verbatim
!>          INFO is INTEGER
!>          0  - successful exit
!>          <0 - if INFO = -i, the i-th argument had an illegal value.
!> \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 DLASCL( TYPE, KL, KU, CFROM, CTO, M, N, A, LDA, INFO )
!
!  -- 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          TYPE
      INTEGER            INFO, KL, KU, LDA, M, N
      DOUBLE PRECISION   CFROM, CTO
!     ..
!     .. Array Arguments ..
      DOUBLE PRECISION   A( LDA, * )
!     ..
!
!  =====================================================================
!
!     .. Parameters ..
      DOUBLE PRECISION   ZERO, ONE
      PARAMETER          ( ZERO = 0.0D0, ONE = 1.0D0 )
!     ..
!     .. Local Scalars ..
      LOGICAL            DONE
      INTEGER            I, ITYPE, J, K1, K2, K3, K4
      DOUBLE PRECISION   BIGNUM, CFROM1, CFROMC, CTO1, CTOC, MUL, SMLNUM
!     ..
!     .. External Functions ..
      LOGICAL            LSAME, DISNAN
      DOUBLE PRECISION   DLAMCH
      EXTERNAL           LSAME, DLAMCH, DISNAN
!     ..
!     .. Intrinsic Functions ..
      INTRINSIC          ABS, MAX, MIN
!     ..
!     .. External Subroutines ..
      EXTERNAL           XERBLA
!     ..
!     .. Executable Statements ..
!
!     Test the input arguments
!
      INFO = 0
!
      IF( LSAME( TYPE, 'G' ) ) THEN
         ITYPE = 0
      ELSE IF( LSAME( TYPE, 'L' ) ) THEN
         ITYPE = 1
      ELSE IF( LSAME( TYPE, 'U' ) ) THEN
         ITYPE = 2
      ELSE IF( LSAME( TYPE, 'H' ) ) THEN
         ITYPE = 3
      ELSE IF( LSAME( TYPE, 'B' ) ) THEN
         ITYPE = 4
      ELSE IF( LSAME( TYPE, 'Q' ) ) THEN
         ITYPE = 5
      ELSE IF( LSAME( TYPE, 'Z' ) ) THEN
         ITYPE = 6
      ELSE
         ITYPE = -1
      END IF
!
      IF( ITYPE.EQ.-1 ) THEN
         INFO = -1
      ELSE IF( CFROM.EQ.ZERO .OR. DISNAN(CFROM) ) THEN
         INFO = -4
      ELSE IF( DISNAN(CTO) ) THEN
         INFO = -5
      ELSE IF( M.LT.0 ) THEN
         INFO = -6
      ELSE IF( N.LT.0 .OR. ( ITYPE.EQ.4 .AND. N.NE.M ) .OR. &
     &         ( ITYPE.EQ.5 .AND. N.NE.M ) ) THEN
         INFO = -7
      ELSE IF( ITYPE.LE.3 .AND. LDA.LT.MAX( 1, M ) ) THEN
         INFO = -9
      ELSE IF( ITYPE.GE.4 ) THEN
         IF( KL.LT.0 .OR. KL.GT.MAX( M-1, 0 ) ) THEN
            INFO = -2
         ELSE IF( KU.LT.0 .OR. KU.GT.MAX( N-1, 0 ) .OR. &
     &            ( ( ITYPE.EQ.4 .OR. ITYPE.EQ.5 ) .AND. KL.NE.KU ) ) &
     &             THEN
            INFO = -3
         ELSE IF( ( ITYPE.EQ.4 .AND. LDA.LT.KL+1 ) .OR. &
     &            ( ITYPE.EQ.5 .AND. LDA.LT.KU+1 ) .OR. &
     &            ( ITYPE.EQ.6 .AND. LDA.LT.2*KL+KU+1 ) ) THEN
            INFO = -9
         END IF
      END IF
!
      IF( INFO.NE.0 ) THEN
         CALL XERBLA( 'DLASCL', -INFO )
         RETURN
      END IF
!
!     Quick return if possible
!
      IF( N.EQ.0 .OR. M.EQ.0 ) &
     &   RETURN
!
!     Get machine parameters
!
      SMLNUM = DLAMCH( 'S' )
      BIGNUM = ONE / SMLNUM
!
      CFROMC = CFROM
      CTOC = CTO
!
   10 CONTINUE
      CFROM1 = CFROMC*SMLNUM
      IF( CFROM1.EQ.CFROMC ) THEN
!        CFROMC is an inf.  Multiply by a correctly signed zero for
!        finite CTOC, or a NaN if CTOC is infinite.
         MUL = CTOC / CFROMC
         DONE = .TRUE.
         CTO1 = CTOC
      ELSE
         CTO1 = CTOC / BIGNUM
         IF( CTO1.EQ.CTOC ) THEN
!           CTOC is either 0 or an inf.  In both cases, CTOC itself
!           serves as the correct multiplication factor.
            MUL = CTOC
            DONE = .TRUE.
            CFROMC = ONE
         ELSE IF( ABS( CFROM1 ).GT.ABS( CTOC ) .AND. CTOC.NE.ZERO ) THEN
            MUL = SMLNUM
            DONE = .FALSE.
            CFROMC = CFROM1
         ELSE IF( ABS( CTO1 ).GT.ABS( CFROMC ) ) THEN
            MUL = BIGNUM
            DONE = .FALSE.
            CTOC = CTO1
         ELSE
            MUL = CTOC / CFROMC
            DONE = .TRUE.
         END IF
      END IF
!
      IF( ITYPE.EQ.0 ) THEN
!
!        Full matrix
!
         DO 30 J = 1, N
            DO 20 I = 1, M
               A( I, J ) = A( I, J )*MUL
   20       CONTINUE
   30    CONTINUE
!
      ELSE IF( ITYPE.EQ.1 ) THEN
!
!        Lower triangular matrix
!
         DO 50 J = 1, N
            DO 40 I = J, M
               A( I, J ) = A( I, J )*MUL
   40       CONTINUE
   50    CONTINUE
!
      ELSE IF( ITYPE.EQ.2 ) THEN
!
!        Upper triangular matrix
!
         DO 70 J = 1, N
            DO 60 I = 1, MIN( J, M )
               A( I, J ) = A( I, J )*MUL
   60       CONTINUE
   70    CONTINUE
!
      ELSE IF( ITYPE.EQ.3 ) THEN
!
!        Upper Hessenberg matrix
!
         DO 90 J = 1, N
            DO 80 I = 1, MIN( J+1, M )
               A( I, J ) = A( I, J )*MUL
   80       CONTINUE
   90    CONTINUE
!
      ELSE IF( ITYPE.EQ.4 ) THEN
!
!        Lower half of a symmetric band matrix
!
         K3 = KL + 1
         K4 = N + 1
         DO 110 J = 1, N
            DO 100 I = 1, MIN( K3, K4-J )
               A( I, J ) = A( I, J )*MUL
  100       CONTINUE
  110    CONTINUE
!
      ELSE IF( ITYPE.EQ.5 ) THEN
!
!        Upper half of a symmetric band matrix
!
         K1 = KU + 2
         K3 = KU + 1
         DO 130 J = 1, N
            DO 120 I = MAX( K1-J, 1 ), K3
               A( I, J ) = A( I, J )*MUL
  120       CONTINUE
  130    CONTINUE
!
      ELSE IF( ITYPE.EQ.6 ) THEN
!
!        Band matrix
!
         K1 = KL + KU + 2
         K2 = KL + 1
         K3 = 2*KL + KU + 1
         K4 = KL + KU + 1 + M
         DO 150 J = 1, N
            DO 140 I = MAX( K1-J, K2 ), MIN( K3, K4-J )
               A( I, J ) = A( I, J )*MUL
  140       CONTINUE
  150    CONTINUE
!
      END IF
!
      IF( .NOT.DONE ) &
     &   GO TO 10
!
      RETURN
!
!     End of DLASCL
!
      END