SRC/dorgrq.f(3)

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version 3.12.1 · 7 versions
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💅 SRC/dorgrq.f(3) — Library Functions Manual 💅

okay bestie, welcome to SRC/dorgrq.f(3) from the Library Functions Manual — this is the DORGRQ page and it is literally giving “orthonormal rows, but make it Fortran” ✨

NAME

SRC/dorgrq.f

SYNOPSIS

🎀 Functions/Subroutines

subroutine dorgrq (m, n, k, a, lda, tau, work, lwork, info)

DORGRQ 👑

Function/Subroutine Documentation

subroutine dorgrq (integer m, integer n, integer k, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) tau, double precision, dimension( * ) work, integer lwork, integer info)

subroutine dorgrq (integer m, integer n, integer k, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( * ) tau, double precision, dimension( * ) work, integer lwork, integer info)

DORGRQ

🌸 Purpose

DORGRQ generates an M-by-N real matrix Q with orthonormal rows. It's defined as the last M rows of a product of K elementary reflectors of order N:

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

as returned by DGERQF. Periodt 💅

✨ Parameters

  • M — M is INTEGER. It's the number of rows of the matrix Q. Constraint: M >= 0. 🫶
  • N — N is INTEGER. It's the number of columns of the matrix Q. Constraint: N >= M. 🌈
  • K — K is INTEGER. It's the number of elementary reflectors whose product defines the matrix Q. Constraint: M >= K >= 0. ⭐
  • A — A is DOUBLE PRECISION array, dimension (LDA,N). On entry, the (m-k+i)-th row must contain the vector which defines the elementary reflector H(i), for i = 1,2,...,k, as returned by DGERQF in the last k rows of its array argument A. On exit, it's the M-by-N matrix Q. iconic behavior, honestly 🔥
  • LDA — LDA is INTEGER. It's the first dimension of the array A. Constraint: LDA >= max(1,M). 💖
  • TAU — TAU is DOUBLE PRECISION array, dimension (K). TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by DGERQF. 🎀
  • 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. It's the dimension of the array WORK. Constraint: LWORK >= max(1,M). For optimum performance, LWORK >= M*NB, 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. iykyk 👀
  • INFO — INFO is INTEGER. = 0: successful exit. < 0: if INFO = -i, the i-th argument has an illegal value. 💀

🌟 Author

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

Definition at line 127 of file dorgrq.f. 🧚

Author

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okay that's the whole page, bestie — source SRC/dorgrq.f(3), LAPACK Version 3.12.0 in the footer, and no date listed so I'm not making one up 💖✨

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