SRC/dopgtr.f(3)

NAME
SRC/dopgtr.f

SYNOPSIS

  Functions/Subroutines
subroutine dopgtr (uplo, n, ap, tau, q, ldq, work, info)
DOPGTR

Function/Subroutine Documentation

  subroutine dopgtr (character uplo, integer n, double precision, dimension( * ) ap, double precision, dimension( * ) tau, double precision, dimension( ldq, * ) q, integer ldq, double precision, dimension( * ) work, integer info)

DOPGTR

Purpose:

    !>
    !> DOPGTR generates a real orthogonal matrix Q which is defined as the
    !> product of n-1 elementary reflectors H(i) of order n, as returned by
    !> DSPTRD using packed storage:
    !>
    !> if UPLO = 'U', Q = H(n-1) . . . H(2) H(1),
    !>
    !> if UPLO = 'L', Q = H(1) H(2) . . . H(n-1).
    !>

Parameters
    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.
    !>

    N

    !>          N is INTEGER
    !>          The order of the matrix Q. N >= 0.
    !>

    AP

    !>          AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
    !>          The vectors which define the elementary reflectors, as
    !>          returned by DSPTRD.
    !>

    TAU

    !>          TAU is DOUBLE PRECISION array, dimension (N-1)
    !>          TAU(i) must contain the scalar factor of the elementary
    !>          reflector H(i), as returned by DSPTRD.
    !>

    Q

    !>          Q is DOUBLE PRECISION array, dimension (LDQ,N)
    !>          The N-by-N orthogonal matrix Q.
    !>

    LDQ

    !>          LDQ is INTEGER
    !>          The leading dimension of the array Q. LDQ >= max(1,N).
    !>

    WORK

    !>          WORK is DOUBLE PRECISION array, dimension (N-1)
    !>

    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 113 of file dopgtr.f.

Author

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