cunghr.f (3)  Linux Manuals
NAME
cunghr.f 
SYNOPSIS
Functions/Subroutines
subroutine cunghr (N, ILO, IHI, A, LDA, TAU, WORK, LWORK, INFO)
CUNGHR
Function/Subroutine Documentation
subroutine cunghr (integerN, integerILO, integerIHI, complex, dimension( lda, * )A, integerLDA, complex, dimension( * )TAU, complex, dimension( * )WORK, integerLWORK, integerINFO)
CUNGHR
Purpose:

CUNGHR generates a complex unitary matrix Q which is defined as the product of IHIILO elementary reflectors of order N, as returned by CGEHRD: 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 CGEHRD. 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 COMPLEX array, dimension (LDA,N) On entry, the vectors which define the elementary reflectors, as returned by CGEHRD. On exit, the NbyN unitary matrix Q.
LDALDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).
TAUTAU is COMPLEX array, dimension (N1) TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CGEHRD.
WORKWORK is COMPLEX 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 cunghr.f.
Author
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