Previous: cunm2l Up: ../lapack-c.html Next: cunmbr

# cunm2r

```
NAME
CUNM2R - overwrite the general complex m-by-n matrix C with
Q * C if SIDE = 'L' and TRANS = 'N', or   Q'* C if SIDE =
'L' and TRANS = 'C', or   C * Q if SIDE = 'R' and TRANS =
'N', or   C * Q' if SIDE = 'R' and TRANS = 'C',

SYNOPSIS
SUBROUTINE CUNM2R( SIDE, TRANS, M, N, K, A, LDA, TAU, C,
LDC, WORK, INFO )

CHARACTER      SIDE, TRANS

INTEGER        INFO, K, LDA, LDC, M, N

COMPLEX        A( LDA, * ), C( LDC, * ), TAU( * ), WORK(
* )

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

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'.

ARGUMENTS
SIDE    (input) CHARACTER*1
= 'L': apply Q or Q' from the Left
= 'R': apply Q or Q' from the Right

TRANS   (input) CHARACTER*1
= 'N': apply Q  (No transpose)
= 'C': apply Q' (Conjugate transpose)

M       (input) INTEGER
The number of rows of the matrix C. M >= 0.

N       (input) INTEGER
The number of columns of the matrix C. N >= 0.

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

TAU     (input) COMPLEX array, dimension (K)
TAU(i) must contain the scalar factor of the elemen-
tary reflector H(i), as returned by CGEQRF.

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

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

WORK    (workspace) COMPLEX array, dimension
(N) if SIDE = 'L', (M) if SIDE = 'R'

INFO    (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal
value
```