---
name: "cunm2l"
section: "3lapack"
platform: "linux"
package: "liblapack-doc"
version: "3.2.1-8"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/cunm2l/3lapack"
---

# cunm2l(3lapack)

overwrites 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',

## NAME

CUNM2L - overwrites 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 CUNM2L(

  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

CUNM2L 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(k) . . . H(2) H(1)\
 as returned by CGEQLF. 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 CGEQLF in the last 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 elementary reflector H(i), as returned by CGEQLF.

- 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