zungtr.f man page

zungtr.f —

Synopsis

Functions/Subroutines

subroutine zungtr (UPLO, N, A, LDA, TAU, WORK, LWORK, INFO)
ZUNGTR

Function/Subroutine Documentation

subroutine zungtr (characterUPLO, integerN, complex*16, dimension( lda, * )A, integerLDA, complex*16, dimension( * )TAU, complex*16, dimension( * )WORK, integerLWORK, integerINFO)

ZUNGTR

Purpose:

ZUNGTR generates a complex unitary matrix Q which is defined as the
product of n-1 elementary reflectors of order N, as returned by
ZHETRD:

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 triangle of A contains elementary reflectors
       from ZHETRD;
= 'L': Lower triangle of A contains elementary reflectors
       from ZHETRD.

N

N is INTEGER
The order of the matrix Q. N >= 0.

A

A is COMPLEX*16 array, dimension (LDA,N)
On entry, the vectors which define the elementary reflectors,
as returned by ZHETRD.
On exit, the N-by-N unitary matrix Q.

LDA

LDA is INTEGER
The leading dimension of the array A. LDA >= N.

TAU

TAU is COMPLEX*16 array, dimension (N-1)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by ZHETRD.

WORK

WORK is COMPLEX*16 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 >= N-1.
For optimum performance LWORK >= (N-1)*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 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 124 of file zungtr.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

zungtr(3) is an alias of zungtr.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK