DORGHR (3)  Linux Man Pages
NAME
dorghr.f 
SYNOPSIS
Functions/Subroutines
subroutine dorghr (N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO)
DORGHR
Function/Subroutine Documentation
subroutine dorghr (integerN, integerILO, integerIHI, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( * )TAU, double precision, dimension( * )WORK, integerLWORK, integerINFO)
DORGHR
Purpose:

DORGHR generates a real orthogonal matrix Q which is defined as the product of IHIILO elementary reflectors of order N, as returned by DGEHRD: Q = H(ilo) H(ilo+1) . . . H(ihi1).
Parameters:

N
N is INTEGER The order of the matrix Q. N >= 0.
ILOILO is INTEGER
IHIIHI is INTEGER ILO and IHI must have the same values as in the previous call of DGEHRD. Q is equal to the unit matrix except in the submatrix Q(ilo+1:ihi,ilo+1:ihi). 1 <= ILO <= IHI <= N, if N > 0; ILO=1 and IHI=0, if N=0.
AA is DOUBLE PRECISION array, dimension (LDA,N) On entry, the vectors which define the elementary reflectors, as returned by DGEHRD. On exit, the NbyN orthogonal matrix Q.
LDALDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).
TAUTAU is DOUBLE PRECISION array, dimension (N1) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by DGEHRD.
WORKWORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK)) On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORKLWORK is INTEGER The dimension of the array WORK. LWORK >= IHIILO. For optimum performance LWORK >= (IHIILO)*NB, where NB is the optimal blocksize. If LWORK = 1, then a workspace query is assumed; the routine only calculates the optimal size of the WORK array, returns this value as the first entry of the WORK array, and no error message related to LWORK is issued by XERBLA.
INFOINFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith 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 127 of file dorghr.f.
Author
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