SRC/slapmr.f(3)

💖 NAME 💖

SRC/slapmr.f — yep, that's the page, and it lives in the LAPACK Library Functions Manual. This one is fully about the slapmr subroutine: the row-shuffling bestie. No cap.

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

subroutine slapmr (forwrd, m, n, x, ldx, k)
    SLAPMR rearranges rows of a matrix as specified by a permutation vector.

The vibe: you hand it a matrix and a permutation vector, and it does the row rearrangement thing. Slay.

🌈 Function/Subroutine Documentation 🌈

🎀 The subroutine itself 🎀

subroutine slapmr (logical forwrd, integer m, integer n, real, dimension(
       ldx, * ) x, integer ldx, integer, dimension( * ) k)

SLAPMR rearranges rows of a matrix as specified by a permutation vector. — literally the one-liner, bestie.

🔥 Purpose 🔥

Okay so the full tea: it rearranges the rows of the M by N matrix X exactly as the permutation K(1),K(2),...,K(M) of the integers 1,...,M says. Here's the exact move situation:

SLAPMR rearranges the rows of the M by N matrix X as specified
by the permutation K(1),K(2),...,K(M) of the integers 1,...,M.
If FORWRD = .TRUE.,  forward permutation:

     X(K(I),*) is moved X(I,*) for I = 1,2,...,M.

If FORWRD = .FALSE., backward permutation:

     X(I,*) is moved to X(K(I),*) for I = 1,2,...,M.

So forward permutation when FORWRD = .TRUE., and backward permutation when FORWRD = .FALSE.. The direction girlies are different, periodt.

🍓 Parameters 🍓

• FORWRD — FORWRD is LOGICAL. It's .TRUE. for a forward permutation, and .FALSE. for a backward permutation.
• M — M is INTEGER. The number of rows of the matrix X. It has to be M >= 0.
• N — N is INTEGER. The number of columns of the matrix X. It has to be N >= 0.
• X — X is REAL array, dimension (LDX,N). On entry, it's the M by N matrix X. On exit, X contains the permuted matrix X. Iconic behavior.
• LDX — LDX is INTEGER. The leading dimension of the array X, and it's gotta be LDX >= MAX(1,M).
• K — K is INTEGER array, dimension (M). On entry, K contains the permutation vector. K is used as internal workspace, but reset to its original value on output. Bestie cleans up after herself.

👑 Author 👑

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

Definition at line 103 of file slapmr.f.

💅 Author 💅

Generated automatically by Doxygen for LAPACK from the source code.

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And that's the whole page, bestie. It's from LAPACK Version 3.12.0, and the page id is SRC/slapmr.f(3). Byeee 🫶✨