HPL_dlaprnt(3)

💅 HPL_dlaprnt — bestie, it prints your matrix ✨

okay so this is a page from the HPL Library Functions manual, and today we're talking about HPL_dlaprnt(3) — the little function that literally just prints a matrix. no cap. it's giving "I'm a debug print and I know it" energy and honestly? we stan.

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🌸 NAME 🌸

HPL_dlaprnt — Print the matrix A. that's it. that's the whole job. she shows up, she prints, she leaves 💅

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✨ SYNOPSIS ✨

#include "hpl.h"

void HPL_dlaprnt( const int M, const int N, double * A, const int IA,
const int JA, const int LDA, const char * CMATNM );

like, copy that header include exactly bestie, don't be out here improvising 🎀

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🦋 DESCRIPTION 🦋

HPL_dlaprnt prints to standard error an M-by-N matrix A.

periodt. it goes to stderr, not stdout — so if you're piping stuff around and wondering why your matrix ghosted you, that's why. she's loud but she's private 🔥

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👑 ARGUMENTS 👑

• M — (local input) const int. On entry, M specifies the number of rows of A. M must be at least zero. no negative rows, we don't do that here 🙈
• N — (local input) const int. On entry, N specifies the number of columns of A. N must be at least zero. same vibe check as M, keep it ≥ 0 bestie.
• A — (local input) double *. On entry, A points to an array of dimension (LDA,N). that's your matrix right there, the main character 💖
• IA — (local input) const int. On entry, IA specifies the starting row index to be printed. like, where do you want the printing to start row-wise 🎀
• JA — (local input) const int. On entry, JA specifies the starting column index to be printed. and where it starts column-wise. the lil corner you're peeking from ✨
• LDA — (local input) const int. On entry, LDA specifies the leading dimension of the array A. LDA must be at least max(1,M). don't skimp on this one, it's a hard requirement fr fr.
• CMATNM — (local input) const char *. On entry, CMATNM is the name of the matrix to be printed. so you can label your matrix like "A" and it'll show up in the output, cute 🏷️

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🍓 EXAMPLE 🍓

okay so here's a whole little program that slays:

#include "hpl.h"

int main(int argc, char *argv[])
{
   double a[2*2];
   a[0] = 1.0; a[1] = 3.0; a[2] = 2.0; a[3] = 4.0;
   HPL_dlaprnt( 2, 2, a, 0, 0, 2, "A" );
   exit(0); return(0);
}

see how a is a double a[2*2] — four lil guys — and we print a 2-by-2 starting at row 0, column 0, with leading dimension 2, labeled "A". chef's kiss, no notes 👑

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🌈 SEE ALSO 🌈

• HPL_fprintf (3) — go read that one too bestie, they're literally linked.

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💀 real talk: the output goes to standard error, M and N must each be at least zero, and LDA must be at least max(1,M). break those and that's on you, not on her.

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so yeah, that's HPL_dlaprnt(3) from the HPL 2.2 library functions crew, dated February 24, 2016. oldie but a goodie, still serving looks in the group chat 💜🫶 go print a matrix and feel something. mwah 🎀