HPL_dlaswp01T(3)

💖 NAME 💖

HPL_dlaswp01T — copies rows of A into itself and into U. (she's from the HPL Library Functions lineup, bestie 💅)

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✨ SYNOPSIS ✨

#include "hpl.h"

void HPL_dlaswp01T( const int M, const int N, double * A, const int LDA,
double * U, const int LDU, const int * LINDXA, const int * LINDXAU );

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🦋 DESCRIPTION 🦋

Okay so real talk: HPL_dlaswp01T takes scattered rows of A and copies them into A itself and into an array U. Like, both. At once. Multitasking queen 👑

The row offsets in A of the source rows? Those are specified by LINDXA. And where those rows are headed? That's LINDXAU's whole job.

Here's the vibe check on LINDXAU: a positive value means the destination is U. Anything else means it's A. Periodt.

And the lil plot twist 🌸 — rows of A are stored as columns in U. Yes bestie, transposed, we love a layout switcheroo.

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👑 ARGUMENTS 👑

• M (local input) — const int. On entry, M says how many rows of A should be moved within A or copied into U. M must be at least zero. No negatives, she doesn't do that 💀
• N (local input) — const int. On entry, N is the length of the rows of A that should be moved within A or copied into U. N must be at least zero too. Rules are rules 🎀
• A (local input/output) — double *. On entry, A points to an array of dimension (LDA,N). The rows of this array specified by LINDXA should be moved within A or copied into U. She's both the source and the destination, main character energy fr fr ✨
• LDA (local input) — const int. On entry, LDA is the leading dimension of the array A. LDA must be at least MAX(1,M). Do not skip this, the math will simply not math 🙈
• U (local input/output) — double *. On entry, U points to an array of dimension (LDU,M). The rows of A specified by LINDXA are copied within this array U at the positions indicated by positive values of LINDXAU. The rows of A are stored as columns in U. Iconic behaviour honestly 💜
• LDU (local input) — const int. On entry, LDU is the leading dimension of the array U. LDU must be at least MAX(1,N). Yes it's N here and M up there for LDA — that's not a typo, that's just the assignment bestie 😭
• LINDXA (local input) — const int *. On entry, LINDXA is an array of dimension M that contains the local row indexes of A that should be moved within A or copied into U. She's the "where from" list 🍓
• LINDXAU (local input) — const int *. On entry, LINDXAU is an array of dimension M that contains the local row indexes of U where the rows of A should be copied at. This array also contains the local row offsets in A where some of the rows of A should be moved to. A positive value of LINDXAU[i] indicates that the row LINDXA[i] of A should be copied into U at the position LINDXAU[i]; otherwise the row LINDXA[i] of A should be moved at the position -LINDXAU[i] within A. She's the "where to" list and she's carrying a sign bit like a lil secret 🧚

Ngl the LINDXAU sign thing is the whole trick of this function. Positive → into U. Otherwise → moved inside A at -LINDXAU[i]. Read it twice if you need to, no shame 💖

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🌈 SEE ALSO 🌈

The whole friend group, go say hi 👋

• HPL_dlaswp00N(3)
• HPL_dlaswp10N(3)
• HPL_dlaswp01N(3)
• HPL_dlaswp01T(3)
• HPL_dlaswp02N(3)
• HPL_dlaswp03N(3)
• HPL_dlaswp03T(3)
• HPL_dlaswp04N(3)
• HPL_dlaswp04T(3)
• HPL_dlaswp05N(3)
• HPL_dlaswp05T(3)
• HPL_dlaswp06N(3)
• HPL_dlaswp06T(3)

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That's the whole page, bestie, you ate it up 🫶 This one's from HPL 2.2, dated February 24, 2016 — old enough to have a driver's license but still slaying ⭐