HPL_dlacpy(3)

💖 HPL_dlacpy — a lil function from the HPL Library Functions crew 💖

okay bestie, gather round, because today we're talking about HPL_dlacpy from the HPL Library Functions lineup. it's giving "copy that, but make it linear algebra" and honestly? we're obsessed. 🦋

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✨ NAME ✨

HPL_dlacpy — literally just B := A. that's the whole vibe. copy one array into another, no notes. 💅

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🌸 SYNOPSIS 🌸

#include "hpl.h"

void HPL_dlacpy( const int M, const int N, const double * A, const int
LDA, double * B, const int LDB );

like yes, six arguments, but she's worth it. 👑

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🎀 DESCRIPTION 🎀

so what does she actually do? HPL_dlacpy copies an array A into an array B. that's it, that's the plot. main character behaviour: takes the data from A, drops it into B, no drama, no returns, no questions asked. 🫶

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💜 ARGUMENTS 💜

• M (local input) const int — on entry, M says how many rows the arrays A and B have. and listen, M must be at least zero, no negative row counts in this house. 😭
• N (local input) const int — on entry, N says how many columns the arrays A and B have. same rule, bestie: N must be at least zero. ⭐
• A (local input) const double * — on entry, A points to an array of dimension (LDA,N). she's the source, the blueprint, the moment. 🌸
• LDA (local input) const int — on entry, LDA is the leading dimension of the array A. and LDA must be at least MAX(1,M). don't test her. 🙈
• B (local output) double * — on entry, B points to an array of dimension (LDB,N). on exit, B is overwritten with A. so like… bye bye old B, hello glow-up. 💖
• LDB (local input) const int — on entry, LDB is the leading dimension of the array B. LDB must be at least MAX(1,M) — same energy as LDA, fr fr. 🔥

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🌈 EXAMPLE 🌈

here's a lil demo so you can see her in action, no cap:

#include "hpl.h"

int main(int argc, char *argv[])
{
   double a[2*2], b[2*2];
   a[0] = 1.0; a[1] = 3.0; a[2] = 2.0; a[3] = 4.0;
   HPL_dlacpy( 2, 2, a, 2, b, 2 );
   printf("  [%f,%f]\n", b[0], b[2]);
   printf("b=[%f,%f]\n", b[1], b[3]);
   exit(0);
   return(0);
}

she ate and left absolutely no crumbs. 🍓

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🦋 SEE ALSO 🦋

• HPL_dlatcpy (3) — her cousin, also iconic, go say hi. ✨

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lowkey reminder: LDA and LDB both gotta be at least MAX(1,M) and M and N both gotta be at least zero. she's chill but she's not that chill. 💀

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and that's the whole page, bestie!! this one's from HPL 2.2, dated February 24, 2016 — oldie but a goodie, and yes she still serves. mwah 💅💖🧚