dorm22.f(3)

NAME
dorm22.f

SYNOPSIS

  Functions/Subroutines
subroutine dorm22 (SIDE, TRANS, M, N, N1, N2, Q, LDQ, C, LDC, WORK, LWORK, INFO)
DORM22 multiplies a general matrix by a banded orthogonal matrix.

Function/Subroutine Documentation

  subroutine dorm22 (character SIDE, character TRANS, integer M, integer N, integer N1, integer N2, double precision, dimension( ldq, * ) Q, integer LDQ, double precision, dimension( ldc, * ) C, integer LDC, double precision, dimension( * ) WORK, integer LWORK, integer INFO)

Purpose

      DORM22 overwrites the general real M-by-N matrix C with
                      SIDE = 'L'     SIDE = 'R'
      TRANS = 'N':      Q * C          C * Q
      TRANS = 'T':      Q**T * C       C * Q**T
      where Q is a real orthogonal matrix of order NQ, with NQ = M if
      SIDE = 'L' and NQ = N if SIDE = 'R'.
      The orthogonal matrix Q processes a 2-by-2 block structure
             [  Q11  Q12  ]
         Q = [            ]
             [  Q21  Q22  ],
      where Q12 is an N1-by-N1 lower triangular matrix and Q21 is an
      N2-by-N2 upper triangular matrix.

Parameters
    SIDE

              SIDE is CHARACTER*1
              = 'L': apply Q or Q**T from the Left;
              = 'R': apply Q or Q**T from the Right.

    TRANS

              TRANS is CHARACTER*1
              = 'N':  apply Q (No transpose);
              = 'C':  apply Q**T (Conjugate transpose).

    M

              M is INTEGER
              The number of rows of the matrix C. M >= 0.

    N

              N is INTEGER
              The number of columns of the matrix C. N >= 0.

    N1
    N2

              N1 is INTEGER
              N2 is INTEGER
              The dimension of Q12 and Q21, respectively. N1, N2 >= 0.
              The following requirement must be satisfied:
              N1 + N2 = M if SIDE = 'L' and N1 + N2 = N if SIDE = 'R'.

    Q

              Q is DOUBLE PRECISION array, dimension
                                           (LDQ,M) if SIDE = 'L'
                                           (LDQ,N) if SIDE = 'R'

    LDQ

              LDQ is INTEGER
              The leading dimension of the array Q.
              LDQ >= max(1,M) if SIDE = 'L'; LDQ >= max(1,N) if SIDE = 'R'.

    C

              C is DOUBLE PRECISION array, dimension (LDC,N)
              On entry, the M-by-N matrix C.
              On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q.

    LDC

              LDC is INTEGER
              The leading dimension of the array C. LDC >= max(1,M).

    WORK

              WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
              On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

    LWORK

              LWORK is INTEGER
              The dimension of the array WORK.
              If SIDE = 'L', LWORK >= max(1,N);
              if SIDE = 'R', LWORK >= max(1,M).
              For optimum performance LWORK >= M*N.
              If LWORK = -1, then a workspace query is assumed; the routine
              only calculates the optimal size of the WORK array, returns
              this value as the first entry of the WORK array, and no error
              message related to LWORK is issued by XERBLA.

    INFO

              INFO is INTEGER
              = 0:  successful exit
              < 0:  if INFO = -i, the i-th argument had an illegal value

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 161 of file dorm22.f.

Author

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