# zunmr2 (3) - Linux Manuals

zunmr2.f -

## SYNOPSIS

### Functions/Subroutines

subroutine zunmr2 (SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, INFO)
ZUNMR2 multiplies a general matrix by the unitary matrix from a RQ factorization determined by cgerqf (unblocked algorithm).

## Function/Subroutine Documentation

### subroutine zunmr2 (characterSIDE, characterTRANS, integerM, integerN, integerK, complex*16, dimension( lda, * )A, integerLDA, complex*16, dimension( * )TAU, complex*16, dimension( ldc, * )C, integerLDC, complex*16, dimension( * )WORK, integerINFO)

ZUNMR2 multiplies a general matrix by the unitary matrix from a RQ factorization determined by cgerqf (unblocked algorithm).

Purpose:

``` ZUNMR2 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 H(2)**H . . . H(k)**H

as returned by ZGERQF. 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*16 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
ZGERQF 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*16 array, dimension (K)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by ZGERQF.
```

C

```          C is COMPLEX*16 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*16 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