SRC/zunmr2.f(3)

💖 SRC/zunmr2.f(3) — Library Functions Manual

💖 NAME

SRC/zunmr2.f — that's the file this whole page is about, bestie. 🫶

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✨ SYNOPSIS

🌈 Functions/Subroutines

subroutine zunmr2 (side, trans, m, n, k, a, lda, tau, c, ldc, work,
     info)

ZUNMR2 multiplies a general matrix by the unitary matrix from an RQ factorization determined by cgerqf (unblocked algorithm). Slay. 💅

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🦋 Function/Subroutine Documentation

subroutine zunmr2 (character side, character trans, integer m, integer n,
     integer k, complex*16, dimension( lda, * ) a, integer lda, complex*16,
     dimension( * ) tau, complex*16, dimension( ldc, * ) c, integer ldc,
     complex*16, dimension( * ) work, integer info)

ZUNMR2 multiplies a general matrix by the unitary matrix from an RQ factorization determined by cgerqf (unblocked algorithm). No cap, that's literally the whole vibe. 🌸

💫 Purpose

okay so here's the main-character moment, fr fr:

ZUNMR2 overwrites the general complex m-by-n matrix C with:

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

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

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

      C * Q**H if SIDE = 'R' and TRANS = 'C',

where Q is a complex unitary matrix defined as the product of k elementary reflectors:

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

as returned by ZGERQF. Q is of order m if SIDE = 'L' and of order n if SIDE = 'R'. Iconic behavior, honestly. 👑

🎀 Parameters

• SIDE — SIDE is CHARACTER*1, the side selector:
  • = 'L': apply Q or Q**H from the Left
  • = 'R': apply Q or Q**H from the Right
• TRANS — TRANS is CHARACTER*1, the transpose selector:
  • = '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.
• 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 COMPLEX*16 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 ZGERQF in the last k rows of its array argument A.
  • A is modified by the routine but restored on exit. cute of it, honestly. 🎀
• LDA — LDA is INTEGER; the leading dimension of the array A. LDA >= max(1,K).
• TAU — TAU is COMPLEX*16 array, dimension (K).
  • TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by ZGERQF.
• 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 (N) if SIDE = 'L', (M) if SIDE = 'R'.
• INFO — INFO is INTEGER.
  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value

bestie, those dimension checks are not a drill — respect the bounds. 💀✨

🌸 Author

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

Definition at line 157 of file zunmr2.f.

🫶 Author

Generated automatically by Doxygen for LAPACK from the source code.

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byeee bestie 💋 — this cutie is from LAPACK Version 3.12.0, page SRC/zunmr2.f(3); the date isn't printed on this page, so consider this your official cute sign-off. ✨🦋