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# cunm2r.f

cunm2r.f −

## SYNOPSIS

Functions/Subroutines

subroutine cunm2r (SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, INFO)
CUNM2R
multiplies a general matrix by the unitary matrix from a QR factorization determined by cgeqrf (unblocked algorithm).

## Function/Subroutine Documentation

subroutine cunm2r (characterSIDE, characterTRANS, integerM, integerN, integerK, complex, dimension( lda, * )A, integerLDA, complex, dimension( * )TAU, complex, dimension( ldc, * )C, integerLDC, complex, dimension( * )WORK, integerINFO)
CUNM2R
multiplies a general matrix by the unitary matrix from a QR factorization determined by cgeqrf (unblocked algorithm).

Purpose:

CUNM2R overwrites the general complex m-by-n matrix C with

Q * C if SIDE = ’L’ and TRANS = ’N’, or

Q**H* C if SIDE = ’L’ and TRANS = ’C’, or

C * Q if SIDE = ’R’ and TRANS = ’N’, or

C * Q**H if SIDE = ’R’ and TRANS = ’C’,

where Q is a complex unitary matrix defined as the product of k
elementary reflectors

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

as returned by CGEQRF. Q is of order m if SIDE = ’L’ and of order n
if SIDE = ’R’.

Parameters:

SIDE

SIDE is CHARACTER*1
= ’L’: apply Q or Q**H from the Left
= ’R’: apply Q or Q**H from the Right

TRANS

TRANS is CHARACTER*1
= ’N’: apply Q (No transpose)
= ’C’: apply Q**H (Conjugate transpose)

M

M is INTEGER
The number of rows of the matrix C. M >= 0.

N

N is INTEGER
The number of columns of the matrix C. N >= 0.

K

K is INTEGER
The number of elementary reflectors whose product defines
the matrix Q.
If SIDE = ’L’, M >= K >= 0;
if SIDE = ’R’, N >= K >= 0.

A

A is COMPLEX array, dimension (LDA,K)
The i-th column must contain the vector which defines the
elementary reflector H(i), for i = 1,2,...,k, as returned by
CGEQRF in the first k columns of its array argument A.
A is modified by the routine but restored on exit.

LDA

LDA is INTEGER
The leading dimension of the array A.
If SIDE = ’L’, LDA >= max(1,M);
if SIDE = ’R’, LDA >= max(1,N).

TAU

TAU is COMPLEX array, dimension (K)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by CGEQRF.

C

C is COMPLEX array, dimension (LDC,N)
On entry, the m-by-n matrix C.
On exit, C is overwritten by Q*C or Q**H*C or C*Q**H or C*Q.

LDC

LDC is INTEGER
The leading dimension of the array C. LDC >= max(1,M).

WORK

WORK is COMPLEX array, dimension
(N) if SIDE = ’L’,
(M) if SIDE = ’R’

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

NAG Ltd.

Date:

September 2012

Definition at line 159 of file cunm2r.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

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