DORMQR(3)

🌸 NAME 🌸

Okay bestie, strap in — this is dormqr.f(3) from the Library Functions Manual, and the full file path is literally:

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

That's the whole NAME section, no cap. 💅

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✨ SYNOPSIS ✨

Under Functions/Subroutines, the quick vibe check is:

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

DORMQR. Iconic. 💖

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💖 Function/Subroutine Documentation 💖

Here's the full signature, bestie — every type, every dimension, exactly as written:

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

DORMQR. That's the name, main character energy. ✨

🎯 Purpose 🎯

DORMQR overwrites the general real M-by-N matrix C with:

                 SIDE = 'L'     SIDE = 'R'
TRANS = 'N':      Q * C          C * Q
TRANS = 'T':      Q**T * C       C * Q**T

where Q is a real orthogonal matrix defined as the product of k elementary reflectors:

       Q = H(1) H(2) . . . H(k)

as returned by DGEQRF. Q is of order M if SIDE = 'L' and of order N if SIDE = 'R'. Slay. 🌈

🌈 Parameters 🌈

💫 SIDE

SIDE is CHARACTER*1

• = 'L': apply Q or Q**T from the Left;
• = 'R': apply Q or Q**T from the Right.

🦋 TRANS

TRANS is CHARACTER*1

• = 'N': No transpose, apply Q;
• = 'T': Transpose, apply Q**T.

🍓 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 DOUBLE PRECISION 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 DGEQRF 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 DOUBLE PRECISION array, dimension (K)

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

🌺 C

C is DOUBLE PRECISION array, dimension (LDC,N)

On entry, the M-by-N matrix C. On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q.

🫶 LDC

LDC is INTEGER

The leading dimension of the array C. LDC >= max(1,M).

🔥 WORK

WORK is DOUBLE PRECISION 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 at line 165 of file dormqr.f.

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🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code.

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And that's the whole page, bestie! Cute sign-off: this was LAPACK Version 3.12.0, path /home/abui...RC/dormqr.f(3). Periodt. 💖✨