DORMRZ(3)

NAME

Okay bestie, welcome to DORMRZ(3) — yes, the LAPACK Library Functions Manual page for DORMRZ — and the NAME section is literally this whole path: /home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dormrz.f. That's it. That's the name. Iconic, honestly. 💅

SYNOPSIS

Functions/Subroutines

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

So yeah, it's DORMRZ, and she has a lot of arguments. It's giving "I have a lot to say" energy. 💖

Function/Subroutine Documentation

Here's the full documented signature, bestie:

   subroutine DORMRZ (character side, character trans, integer m, integer n,
       integer k, integer l, 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)

The subroutine name is DORMRZ. Periodt. 🎀

Purpose

DORMRZ 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 DTZRZF. Q is of order M if SIDE = 'L' and of order N if SIDE = 'R'. No cap, that's the whole purpose. 🦋

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.
• L — L is INTEGER. The number of columns of the matrix A containing the meaningful part of the Householder reflectors. If SIDE = 'L', M >= L >= 0, if SIDE = 'R', N >= L >= 0.
• A — A is DOUBLE PRECISION array, dimension (LDA,M) if SIDE = 'L', (LDA,N) if SIDE = 'R'. The i-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DTZRZF in the last k rows of its array argument A. A is modified by the routine but restored on exit.
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,K).
• TAU — TAU is DOUBLE PRECISION array, dimension (K). TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by DTZRZF.
• 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**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 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.

Contributors:

A. Petitet, Computer Science Dept., Univ. of Tenn., Knoxville, USA

Further Details:

The source has an empty !> block here, so there's literally no extra tea to spill. 💀

Definition at line 185 of file dormrz.f.

That's the exact spot: Definition at line 185 of file dormrz.f. ✨

Author

Generated automatically by Doxygen for LAPACK from the source code.

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That's the whole vibe, bestie. Footer check: LAPACK Version 3.12.0, and the page path is /home/abui...RC/dormrz.f(3). Byeee, go slay those Householder reflectors. 💖✨🦋