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zung2l.f(3) LAPACK zung2l.f(3)

NAME

zung2l.f -

SYNOPSIS

Functions/Subroutines


subroutine zung2l (M, N, K, A, LDA, TAU, WORK, INFO)
 
ZUNG2L generates all or part of the unitary matrix Q from a QL factorization determined by cgeqlf (unblocked algorithm).

Function/Subroutine Documentation

subroutine zung2l (integerM, integerN, integerK, complex*16, dimension( lda, * )A, integerLDA, complex*16, dimension( * )TAU, complex*16, dimension( * )WORK, integerINFO)

ZUNG2L generates all or part of the unitary matrix Q from a QL factorization determined by cgeqlf (unblocked algorithm).
Purpose: 
 ZUNG2L generates an m by n complex matrix Q with orthonormal columns,
 which is defined as the last n columns of a product of k elementary
 reflectors of order m


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


 as returned by ZGEQLF.
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 COMPLEX*16 array, dimension (LDA,N)
          On entry, the (n-k+i)-th column must contain the vector which
          defines the elementary reflector H(i), for i = 1,2,...,k, as
          returned by ZGEQLF in the last 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 COMPLEX*16 array, dimension (K)
          TAU(i) must contain the scalar factor of the elementary
          reflector H(i), as returned by ZGEQLF.
WORK 
          WORK is COMPLEX*16 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 zung2l.f.

Author

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