SRC/dopmtr.f(3)

NAME
SRC/dopmtr.f

SYNOPSIS

  Functions/Subroutines
subroutine dopmtr (side, uplo, trans, m, n, ap, tau, c, ldc, work, info)
DOPMTR

Function/Subroutine Documentation

  subroutine dopmtr (character side, character uplo, character trans, integer m, integer n, double precision, dimension( * ) ap, double precision, dimension( * ) tau, double precision, dimension( ldc, * ) c, integer ldc, double precision, dimension( * ) work, integer info)

DOPMTR

Purpose:

    !>
    !> DOPMTR 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'. Q is defined as the product of
    !> nq-1 elementary reflectors, as returned by DSPTRD using packed
    !> storage:
    !>
    !> if UPLO = 'U', Q = H(nq-1) . . . H(2) H(1);
    !>
    !> if UPLO = 'L', Q = H(1) H(2) . . . H(nq-1).
    !>

Parameters
    SIDE

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

    UPLO

    !>          UPLO is CHARACTER*1
    !>          = 'U': Upper triangular packed storage used in previous
    !>                 call to DSPTRD;
    !>          = 'L': Lower triangular packed storage used in previous
    !>                 call to DSPTRD.
    !>

    TRANS

    !>          TRANS is CHARACTER*1
    !>          = 'N':  No transpose, apply Q;
    !>          = 'T':  Transpose, apply Q**T.
    !>

    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.
    !>

    AP

    !>          AP is DOUBLE PRECISION array, dimension
    !>                               (M*(M+1)/2) if SIDE = 'L'
    !>                               (N*(N+1)/2) if SIDE = 'R'
    !>          The vectors which define the elementary reflectors, as
    !>          returned by DSPTRD.  AP is modified by the routine but
    !>          restored on exit.
    !>

    TAU

    !>          TAU is DOUBLE PRECISION array, dimension (M-1) if SIDE = 'L'
    !>                                     or (N-1) if SIDE = 'R'
    !>          TAU(i) must contain the scalar factor of the elementary
    !>          reflector H(i), as returned by DSPTRD.
    !>

    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
    !>                                   (N) if SIDE = 'L'
    !>                                   (M) if SIDE = 'R'
    !>

    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 148 of file dopmtr.f.

Author

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