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

# cupmtr(3lapack)

overwrites the general complex M-by-N matrix C with SIDE = 'L' SIDE = 'R' TRANS = 'N'

## NAME

CUPMTR - overwrites the general complex M-by-N matrix C with   SIDE = 'L' SIDE = 'R' TRANS = 'N'

## SYNOPSIS

- SUBROUTINE CUPMTR(

  SIDE, UPLO, TRANS, M, N, AP, TAU, C, LDC, WORK, INFO )

- CHARACTER

  SIDE, TRANS, UPLO

- INTEGER

  INFO, LDC, M, N

- COMPLEX

  AP( \* ), C( LDC, \* ), TAU( \* ), WORK( \* )

## PURPOSE

CUPMTR overwrites the general complex M-by-N matrix C with TRANS = 'C':      Q\*\*H \* C       C \* Q\*\*H\
 where Q is a complex unitary matrix of order nq, with nq = m if SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of nq-1 elementary reflectors, as returned by CHPTRD using packed storage:\
 if UPLO = 'U', Q = H(nq-1) . . . H(2) H(1);\
 if UPLO = 'L', Q = H(1) H(2) . . . H(nq-1).\

## ARGUMENTS

- SIDE (input) CHARACTER\*1

  \= 'L': apply Q or Q\*\*H from the Left;\
   \= 'R': apply Q or Q\*\*H from the Right.

- UPLO (input) CHARACTER\*1

  \= 'U': Upper triangular packed storage used in previous call to CHPTRD; = 'L': Lower triangular packed storage used in previous call to CHPTRD.

- TRANS (input) CHARACTER\*1

  \= 'N':  No transpose, apply Q;\
   \= 'C':  Conjugate transpose, apply Q\*\*H.

- 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.

- AP (input) COMPLEX array, dimension

  (M\*(M+1)/2) if SIDE = 'L' (N\*(N+1)/2) if SIDE = 'R' The vectors which define the elementary reflectors, as returned by CHPTRD.  AP is modified by the routine but restored on exit.

- TAU (input) COMPLEX array, dimension (M-1) if SIDE = 'L'

  or (N-1) if SIDE = 'R' TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CHPTRD.

- 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\*\*H\*C or C\*Q\*\*H 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