dopgtr.f File Reference

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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

Download DOPGTR + dependencies [TGZ] [ZIP] [TXT]

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:

[in]	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.
[in]	N	N is INTEGER The order of the matrix Q. N >= 0.
[in]	AP	AP is DOUBLE PRECISION array, dimension (N*(N+1)/2) The vectors which define the elementary reflectors, as returned by DSPTRD.
[in]	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.
[out]	Q	Q is DOUBLE PRECISION array, dimension (LDQ,N) The N-by-N orthogonal matrix Q.
[in]	LDQ	LDQ is INTEGER The leading dimension of the array Q. LDQ >= max(1,N).
[out]	WORK	WORK is DOUBLE PRECISION array, dimension (N-1)
[out]	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.

Date:

November 2011

Definition at line 115 of file dopgtr.f.

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