ZUNMTR(3)

okay bestie, welcome to ZUNMTR(3) from LAPACK — the Library Functions Manual page for this file — and the header is showing /home/abui...RC/zunmtr.f(3). No cap, it’s giving “we’re deep in the LAPACK source tree” energy already 💅

💖 NAME 💖

This one is lowkey just the full path, bestie:

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

That’s it. That’s the NAME section. periodt 💀

✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

subroutine ZUNMTR (side, uplo, trans, m, n, a, lda, tau, c, ldc, work,
    lwork, info)

And then it’s literally just:

ZUNMTR

👑 Function/Subroutine Documentation 👑

subroutine ZUNMTR (character side, character uplo, character trans, integer
    m, integer n, complex*16, dimension( lda, * ) a, integer lda,
    complex*16, dimension( * ) tau, complex*16, dimension( ldc, * ) c,
    integer ldc, complex*16, dimension( * ) work, integer lwork, integer
    info)

ZUNMTR

🌸 Purpose 🌸

Okay so ZUNMTR 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'. Say it with me: Q is defined as the product of nq-1 elementary reflectors, as returned by ZHETRD:

if UPLO = 'U', Q = H(nq-1) . . . H(2) H(1);

if UPLO = 'L', Q = H(1) H(2) . . . H(nq-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.

🦋 UPLO

UPLO is CHARACTER*1

• = 'U': Upper triangle of A contains elementary reflectors from ZHETRD;
• = 'L': Lower triangle of A contains elementary reflectors from ZHETRD.

🌈 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.

💅 A

A is COMPLEX*16 array, dimension

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

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

✨ 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*16 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 ZHETRD.

🧚 C

C is COMPLEX*16 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*16 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.

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 169 of file zunmtr.f.

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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