dopgtr.f (3) Linux Manual Page

dopgtr.f –

Synopsis

Functions/Subroutines

subroutine dopgtr (UPLO, N, AP, TAU, Q, LDQ, WORK, INFO)
DOPGTR

Function/Subroutine Documentation

subroutine dopgtr (characterUPLO, integerN, double precision, dimension( * )AP, double precision, dimension( * )TAU, double precision, dimension( ldq, * )Q, integerLDQ, double precision, dimension( * )WORK, integerINFO)

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.

Date:

November 2011

Definition at line 115 of file dopgtr.f.

Author

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