CUNMHR(3)

CUNMHR(3) — Library Functions Manual

okay so bestie 💅 this page lives at /home/abui...RC/cunmhr.f(3), and the manual name is Library Functions Manual. It’s giving serious LAPACK function-documentation energy, so let’s get into it. ✨

🌸 NAME

The NAME line is literally the source path, no cute nickname:

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

✨ SYNOPSIS

Functions/Subroutines

subroutine CUNMHR (side, trans, m, n, ilo, ihi, a, lda, tau, c, ldc,
    work, lwork, info)
    CUNMHR

💫 Function/Subroutine Documentation

Here’s the full signature, character for character, no cap:

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

🎀 Purpose

CUNMHR 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 of order nq, with nq = m if SIDE = 'L' and nq = n if SIDE = 'R'. Q is defined as the product of IHI-ILO elementary reflectors, as returned by CGEHRD:

Q = H(ilo) H(ilo+1) . . . H(ihi-1).

🔥 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.

ILO

ILO is INTEGER

IHI

IHI is INTEGER

ILO and IHI must have the same values as in the previous call of CGEHRD. Q is equal to the unit matrix except in the submatrix Q(ilo+1:ihi,ilo+1:ihi).

If SIDE = 'L', then 1 <= ILO <= IHI <= M, if M > 0, and ILO = 1 and IHI = 0, if M = 0; if SIDE = 'R', then 1 <= ILO <= IHI <= N, if N > 0, and ILO = 1 and IHI = 0, if N = 0.

A

A is COMPLEX array, dimension

                    (LDA,M) if SIDE = 'L'
                    (LDA,N) if SIDE = 'R'

The vectors which define the elementary reflectors, as returned by CGEHRD.

LDA

LDA is INTEGER

The leading dimension of the array A.

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

TAU

TAU is COMPLEX array, dimension

                    (M-1) if SIDE = 'L'
                    (N-1) if SIDE = 'R'

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

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 optimum performance LWORK >= N*NB if SIDE = 'L', and LWORK >= M*NB if SIDE = 'R', where NB is the optimal blocksize.

workspace-query alert 🫶 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 at line 177 of file cunmhr.f.

👑 Author

Generated automatically by Doxygen for LAPACK from the source code.

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mwah 💋 that’s the whole vibe: source/version is LAPACK Version 3.12.0, page path is /home/abui...RC/cunmhr.f(3), and there’s no date shown in the original footer, so I’m not inventing one. slay, bestie 🌈💖