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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