
cunghr.f(3) LAPACK cunghr.f(3)
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.
ILO
ILO is INTEGER
IHI
IHI 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.
A
A 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.
LDA
LDA is INTEGER
The leading dimension of the array A. LDA >= max(1,N).
TAU
TAU is COMPLEX array, dimension (N1)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by CGEHRD.
WORK
WORK is COMPLEX array, dimension (MAX(1,LWORK))
On exit, if INFO = 0, WORK(1) returns the optimal LWORK.
LWORK
LWORK 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.
INFO
INFO 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
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 cunghr.f(3) 
