CUNMQR(3)

📦 version 3.12.0, in opensuse-leap 16.0

okay bestie, welcome to cunmqr.f(3) from the Library Functions Manual 🫶 — the header path says /home/abui...RC/cunmqr.f(3), and we are about to get into some complex unitary matrix business. no cap.

NAME 🎀

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/cunmqr.f

SYNOPSIS ✨

Functions/Subroutines

  • subroutine CUNMQR (side, trans, m, n, k, a, lda, tau, c, ldc, work, lwork, info) — CUNMQR

💫 Function/Subroutine Documentation 💫

subroutine CUNMQR (character side, character trans, integer m, integer n,
     integer k, complex, dimension( lda, * ) a, integer lda, complex,
     dimension( * ) tau, complex, dimension( ldc, * ) c, integer ldc,
     complex, dimension( * ) work, integer lwork, integer info)

CUNMQR

Purpose 🌈

CUNMQR 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:

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'.

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.

A

A is 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.

LDA

LDA is INTEGER.

The leading dimension of the array A.

If SIDE = 'L', LDA >= max(1,M);

if SIDE = 'R', LDA >= max(1,N).

TAU

TAU is COMPLEX array, dimension (K).

TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CGEQRF.

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 good performance, LWORK should generally be larger.

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.

Definition 📌

Definition at line 166 of file cunmqr.f.

Author 🤖

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