cunmrz.f −

**Functions/Subroutines**

subroutine **cunmrz** (SIDE, TRANS, M, N, K, L, A, LDA, TAU, C, LDC, WORK, LWORK, INFO)

CUNMRZ

**subroutine cunmrz (characterSIDE, characterTRANS, integerM, integerN, integerK, integerL, complex, dimension( lda, * )A, integerLDA, complex, dimension( * )TAU, complex, dimension( ldc, * )C, integerLDC, complex, dimension( * )WORK, integerLWORK, integerINFO)
CUNMRZ**

**Purpose:**

CUNMRZ overwrites the general complex M-by-N matrix C with

SIDE = ’L’ SIDE = ’R’

TRANS = ’N’: Q * C C * Q

TRANS = ’C’: Q**H * C C * Q**H

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

elementary reflectors

as returned by CTZRZF. 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’: No transpose, apply Q;

= ’C’: Conjugate transpose, apply Q**H.

*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.

*L*

L is INTEGER

The number of columns of the matrix A containing

the meaningful part of the Householder reflectors.

If SIDE = ’L’, M >= L >= 0, if SIDE = ’R’, N >= L >= 0.

*A*

A is COMPLEX array, dimension

(LDA,M) if SIDE = ’L’,

(LDA,N) if SIDE = ’R’

The i-th row must contain the vector which defines the

elementary reflector H(i), for i = 1,2,...,k, as returned by

CTZRZF in the last k rows 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. LDA >= max(1,K).

*TAU*

TAU is COMPLEX array, dimension (K)

TAU(i) must contain the scalar factor of the elementary

reflector H(i), as returned by CTZRZF.

*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 (MAX(1,LWORK))

On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

*LWORK*

LWORK is INTEGER

The dimension of the array WORK.

If SIDE = ’L’, LWORK >= max(1,N);

if SIDE = ’R’, LWORK >= max(1,M).

For optimum performance LWORK >= N*NB if SIDE = ’L’, and

LWORK >= M*NB if SIDE = ’R’, 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

**Contributors:**

A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

**Further Details:**

Definition at line 189 of file cunmrz.f.

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