SRC/sormr2.f(3)

okay bestie, this is the Library Functions Manual page for SRC/sormr2.f(3) — yes, that SRC/sormr2.f — and the function in the spotlight is sormr2. Buckle up, because this unblocked-algorithm icon is about to multiply a general matrix by the orthogonal matrix from an RQ factorization. 💅✨

NAME

SRC/sormr2.f — the manual page title, and sormr2 is the subroutine you came here for. 🎀

SYNOPSIS

Functions/Subroutines

subroutine sormr2 (side, trans, m, n, k, a, lda, tau, c, ldc, work,
    info)
    SORMR2 multiplies a general matrix by the orthogonal matrix from a
    RQ factorization determined by sgerqf (unblocked algorithm).

That's the whole synopsis vibe, bestie. 🫶

Function/Subroutine Documentation

subroutine sormr2 💖

subroutine sormr2 (character side, character trans, integer m, integer n,
    integer k, real, dimension( lda, * ) a, integer lda, real, dimension( *
    ) tau, real, dimension( ldc, * ) c, integer ldc, real, dimension( * )
    work, integer info)

SORMR2 multiplies a general matrix by the orthogonal matrix from a RQ factorization determined by sgerqf (unblocked algorithm). That's literally the whole main-character job. 👑

Purpose

Here's the exact overwrite tea: SORMR2 overwrites the general real m by n matrix C with

Q * C  if SIDE = 'L' and TRANS = 'N', or

Q**T* C  if SIDE = 'L' and TRANS = 'T', or

C * Q  if SIDE = 'R' and TRANS = 'N', or

C * Q**T if SIDE = 'R' and TRANS = '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 SGERQF. Q is of order m if SIDE = 'L' and of order n if SIDE = 'R'. slay. ✨

Parameters

• SIDE — CHARACTER*1. = 'L': apply Q or Q**T from the Left. = 'R': apply Q or Q**T from the Right.
• TRANS — CHARACTER*1. = 'N': apply Q (No transpose). = 'T': apply Q' (Transpose).
• M — INTEGER. The number of rows of the matrix C. M >= 0.
• N — INTEGER. The number of columns of the matrix C. N >= 0.
• K — 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 — REAL 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 SGERQF in the last k rows of its array argument A. A is modified by the routine but restored on exit.
• LDA — INTEGER. The leading dimension of the array A. LDA >= max(1,K).
• TAU — REAL array, dimension (K). TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SGERQF.
• C — REAL 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 — INTEGER. The leading dimension of the array C. LDC >= max(1,M).
• WORK — REAL array, dimension (N) if SIDE = 'L', (M) if SIDE = 'R'.
• INFO — INTEGER. = 0: successful exit. < 0: if INFO = -i, the i-th argument had an illegal value. 🚨 illegal value alert, bestie 🚨

Author

• Univ. of Tennessee
• Univ. of California Berkeley
• Univ. of Colorado Denver
• NAG Ltd.

Definition at line 157 of file sormr2.f.

Author

This page? Generated automatically by Doxygen for LAPACK from the source code. No cap, that's the meta-author energy. 🫶

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Later bestie! 💖 This was the LAPACK page, Version 3.12.0, for SRC/sormr2.f(3). Mwah. ✨💅