DQPT01(3)

DQPT01(3) 🦋

okay so bestie, welcome to the DQPT01(3) page from the Library Functions Manual. it’s giving “niche LAPACK testing routine that actually ate,” and we’re gonna get through every detail together, no cap. 💅

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NAME

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/TESTING/LIN/dqpt01.f

that’s the file this page is about, bestie — lowkey just the full path, and yes we’re keeping it exactly like that. 🎀

SYNOPSIS

Functions/Subroutines

double precision function DQPT01 (m, n, k, a, af, lda, tau, jpvt, work,
    lwork)

DQPT01

Function/Subroutine Documentation ✨

full signature 🫶

here’s the full signature, character-for-character, because we do not play about exact declarations:

double precision function DQPT01 (integer m, integer n, integer k, double
    precision, dimension( lda, * ) a, double precision, dimension( lda, * )
    af, integer lda, double precision, dimension( * ) tau, integer,
    dimension( * ) jpvt, double precision, dimension( lwork ) work, integer
    lwork)

DQPT01

Purpose

okay so the purpose is literally this: DQPT01 tests the QR-factorization with pivoting of a matrix A. the array AF contains the (possibly partial) QR-factorization of A, where the upper triangle of AF(1:K,1:K) is a partial triangular factor, the entries below the diagonal in the first K columns are the Householder vectors, and the rest of AF contains a partially updated matrix. iconic behavior, honestly. 💖

this function returns:

||A*P - Q*R|| / ( ||norm(A)||*eps*max(M,N) )

where || . || is matrix one norm. periodt. 🦋

Parameters

• M — M is INTEGER, and it’s the number of rows of the matrices A and AF. 🎀
• N — N is INTEGER, and it’s the number of columns of the matrices A and AF. 🌸
• K — K is INTEGER, and it’s the number of columns of AF that have been reduced to upper triangular form. 💅
• A — A is a DOUBLE PRECISION array, dimension (LDA, N), and it’s the original matrix A. 🫶
• AF — AF is a DOUBLE PRECISION array, dimension (LDA,N), and it’s the (possibly partial) output of DGEQPF. the upper triangle of AF(1:k,1:k) is a partial triangular factor, the entries below the diagonal in the first k columns are the Householder vectors, and the rest of AF contains a partially updated matrix. 😭
• LDA — LDA is INTEGER, and it’s the leading dimension of the arrays A and AF. ✨
• TAU — TAU is a DOUBLE PRECISION array, dimension (K), with details of the Householder transformations as returned by DGEQPF. 💜
• JPVT — JPVT is an INTEGER array, dimension (N), with pivot information as returned by DGEQPF. 🌈
• WORK — WORK is a DOUBLE PRECISION array, dimension (LWORK). 🍓
• LWORK — LWORK is INTEGER, and it’s the length of the array WORK. LWORK >= M*N+N. no cap, that condition is mandatory. 🔥

Author

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

Definition at line 119 of file dqpt01.f.

Definition at line 119 of file dqpt01.f. — yup, that’s the exact line-and-file info, bestie. 🧚

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Author

Generated automatically by Doxygen for LAPACK from the source code.

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big kiss and a little sparkle 💖 this whole page is LAPACK Version 3.12.0, source path /home/abui...IN/dqpt01.f(3) — slay, bye! 💅✨