HPL_pdgesv(3)

💖 HPL_pdgesv — bestie's guide to solving A x = b 💖

okay so this is HPL_pdgesv(3), one of the HPL Library Functions, and honestly? it's giving main character. it solves A x = b and it does it in parallel, periodt. 🫶

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✨ SYNOPSIS ✨

#include "hpl.h"

void HPL_pdgesv( HPL_T_grid * GRID, HPL_T_palg * ALGO, HPL_T_pmat * A );

like, that's it. three pointers and a dream. 💅

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🌸 DESCRIPTION 🌸

okay so what this function actually DOES, bestie, is factor a N+1-by-N matrix using LU factorization with row partial pivoting. yes, the real thing. no shortcuts. 🔥

the main algorithm is the "right looking" variant, and it can run with or without look-ahead — so it's flexible, it's adaptable, it's lowkey iconic.

two things to know so you don't get caught off guard:

• the lower triangular factor is left unpivoted 🙈
• and the pivots are not returned 💀

and the right hand side? it's the N+1 column of the coefficient matrix. that's the vibe. that's the whole setup. ✨

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👑 ARGUMENTS 👑

• GRID (local input) HPL_T_grid * — on entry, GRID points to the data structure holding all the process grid information. basically the map of who's where in the parallel universe. 🌈
• ALGO (global input) HPL_T_palg * — on entry, ALGO points to the data structure containing the algorithmic parameters. all the knobs and settings, all the little decisions. 🎀
• A (local input/output) HPL_T_pmat * — on entry, A points to the data structure containing the local array information. it goes in, it comes out changed. that's the input/output life. 💫

ngl, if you're passing the wrong thing into any of these three, the whole thing is not gonna slay. double check your pointers, bestie. 😭

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🦋 SEE ALSO 🦋

• HPL_pdgesv0 (3)
• HPL_pdgesvK1 (3)
• HPL_pdgesvK2 (3)
• HPL_pdtrsv (3)

the whole friend group fr fr. go say hi. 💜

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and that's the tea, bestie — this page is from HPL 2.2, dated February 24, 2016. old but still absolutely eating. no cap. ⭐🧚‍♀️