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dorg2r.f(3) LAPACK dorg2r.f(3)

NAME

dorg2r.f -

SYNOPSIS

Functions/Subroutines


subroutine dorg2r (M, N, K, A, LDA, TAU, WORK, INFO)
 
DORG2R generates all or part of the orthogonal matrix Q from a QR factorization determined by sgeqrf (unblocked algorithm).

Function/Subroutine Documentation

subroutine dorg2r (integerM, integerN, integerK, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( * )TAU, double precision, dimension( * )WORK, integerINFO)

DORG2R generates all or part of the orthogonal matrix Q from a QR factorization determined by sgeqrf (unblocked algorithm).
Purpose: 
 DORG2R generates an m by n real matrix Q with orthonormal columns,
 which is defined as the first n columns of a product of k elementary
 reflectors of order m


       Q  =  H(1) H(2) . . . H(k)


 as returned by DGEQRF.
Parameters:
M 
          M is INTEGER
          The number of rows of the matrix Q. M >= 0.
N 
          N is INTEGER
          The number of columns of the matrix Q. M >= N >= 0.
K 
          K is INTEGER
          The number of elementary reflectors whose product defines the
          matrix Q. N >= K >= 0.
A 
          A is DOUBLE PRECISION array, dimension (LDA,N)
          On entry, the i-th column must contain the vector which
          defines the elementary reflector H(i), for i = 1,2,...,k, as
          returned by DGEQRF in the first k columns of its array
          argument A.
          On exit, the m-by-n matrix Q.
LDA 
          LDA is INTEGER
          The first dimension of the array A. LDA >= max(1,M).
TAU 
          TAU is DOUBLE PRECISION array, dimension (K)
          TAU(i) must contain the scalar factor of the elementary
          reflector H(i), as returned by DGEQRF.
WORK 
          WORK is DOUBLE PRECISION array, dimension (N)
INFO 
          INFO is INTEGER
          = 0: successful exit
          < 0: if INFO = -i, the i-th argument has an illegal value
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 115 of file dorg2r.f.

Author

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