MB01QD

Matrix scaling (lower level routine)

Purpose

  To multiply 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, (block) upper triangular, (block) lower triangular,
  (block) upper Hessenberg, or banded.

      SUBROUTINE MB01QD( TYPE, M, N, KL, KU, CFROM, CTO, NBL, NROWS, A,
     $                   LDA, INFO )
C     .. Scalar Arguments ..
      CHARACTER          TYPE
      INTEGER            INFO, KL, KU, LDA, M, N, NBL
      DOUBLE PRECISION   CFROM, CTO
C     .. Array Arguments ..
      INTEGER            NROWS ( * )
      DOUBLE PRECISION   A( LDA, * )

Mode Parameters

  TYPE    CHARACTER*1
          TYPE indices the storage type of the input matrix.
          = 'G':  A is a full matrix.
          = 'L':  A is a (block) lower triangular matrix.
          = 'U':  A is a (block) upper triangular matrix.
          = 'H':  A is a (block) 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.

  M       (input) INTEGER
          The number of rows of the matrix A.  M >= 0.

  N       (input) INTEGER
          The number of columns of the matrix A.  N >= 0.

  KL      (input) INTEGER
          The lower bandwidth of A.  Referenced only if TYPE = 'B',
          'Q' or 'Z'.

  KU      (input) INTEGER
          The upper bandwidth of A.  Referenced only if TYPE = 'B',
          'Q' or 'Z'.

  CFROM   (input) DOUBLE PRECISION
  CTO     (input) 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.

  NBL     (input) INTEGER
          The number of diagonal blocks of the matrix A, if it has a
          block structure.  To specify that matrix A has no block
          structure, set NBL = 0.  NBL >= 0.

  NROWS   (input) INTEGER array, dimension max(1,NBL)
          NROWS(i) contains the number of rows and columns of the
          i-th diagonal block of matrix A.  The sum of the values
          NROWS(i),  for  i = 1: NBL,  should be equal to min(M,N).
          The array  NROWS  is not referenced if NBL = 0.

  A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
          The matrix to be multiplied by CTO/CFROM.  See TYPE for
          the storage type.

  LDA     (input) INTEGER
          The leading dimension of the array A.  LDA >= max(1,M).

  INFO    INTEGER
          Not used in this implementation.

  Matrix A is multiplied by the real scalar CTO/CFROM, taking into
  account the specified storage mode of the matrix.
  MB01QD is a version of the LAPACK routine DLASCL, modified for
  dealing with block triangular, or block Hessenberg matrices.
  For efficiency, no tests of the input scalar parameters are
  performed.

  None

Program Text

  None

  None

  None

Return to index