SRC/cla_herpvgrw.f(3)

💖 NAME 💖

SRC/cla_herpvgrw.f — bestie, this is the LAPACK source file for cla_herpvgrw, and it's literally the vibe-check function for your LU factorization 🔥

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✨ SYNOPSIS ✨

Functions/Subroutines

real function cla_herpvgrw (uplo, n, info, a, lda, af, ldaf, ipiv, work)

okay so it's called CLA_HERPVGRW and yes it's a real function, she returns a real number, main character energy 💅

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🎀 Function/Subroutine Documentation 🎀

real function cla_herpvgrw (character*1 uplo, integer n, integer info,
    complex, dimension( lda, * ) a, integer lda, complex, dimension( ldaf, *
    ) af, integer ldaf, integer, dimension( * ) ipiv, real, dimension( * )
    work)

CLA_HERPVGRW — say it with me 🗣️

🌸 Purpose 🌸

🫶 CLA_HERPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U). The norm is used. If this is much less than 1, the stability of the LU factorization of the (equilibrated) matrix A could be poor. This also means that the solution X, estimated condition numbers, and error bounds could be unreliable.

fr fr, that's the whole point of her 👑 she's out here telling you whether your factorization is actually serving or just giving false confidence 😭 if that number comes back way under 1, bestie, the LU factorization of the (equilibrated) matrix A could be poor — and the solution X, the estimated condition numbers, and the error bounds could all be unreliable. no cap, treat that as a red flag 🚩

🦋 Parameters 🦋

UPLO

UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.

which triangle of A are we even talking about, pick one 💅 'U' for upper, 'L' for lower, that's it, that's the whole job.

N

N is INTEGER The number of linear equations, i.e., the order of the matrix A. N >= 0.

the number of linear equations, aka the order of the matrix A. and it's gotta be N >= 0, non-negotiable ⭐

INFO

INFO is INTEGER The value of INFO returned from SSYTRF, .i.e., the pivot in column INFO is exactly 0.

this is the INFO that came back from SSYTRF — i.e., the pivot in column INFO is exactly zero 🫠 (yes the original really does say ".i.e.," with the stray dot, I'm just the messenger 🙈)

A

A is COMPLEX array, dimension (LDA,N) On entry, the N-by-N matrix A.

on entry, this is the N-by-N matrix A. complex, obviously, she's fancy 💜

LDA

LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).

the leading dimension of the array A, and it better be LDA >= max(1,N) 🔥

AF

AF is COMPLEX array, dimension (LDAF,N) The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by CHETRF.

this one's carrying the block diagonal matrix D and the multipliers used to obtain the factor U or L, exactly as computed by CHETRF ✨

LDAF

LDAF is INTEGER The leading dimension of the array AF. LDAF >= max(1,N).

the leading dimension of the array AF, LDAF >= max(1,N), same energy, different letter 🎀

IPIV

IPIV is INTEGER array, dimension (N) Details of the interchanges and the block structure of D as determined by CHETRF.

all the deets on the interchanges and the block structure of D, as determined by CHETRF 👑

WORK

WORK is REAL array, dimension (2*N)

WORK is a REAL array, dimension (2*N). that's the whole description, she's lowkey mysterious like that 🧚

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👑 Author 👑

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

Definition at line 121 of file cla_herpvgrw.f.

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code. (not a human, just a robot doing her little tasks 🤖💖)

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🍓 ok so that's the whole page! this one's from LAPACK, Version 3.12.0, living at SRC/cla_herpvgrw.f(3) — go be iconic with your pivot growth factors, bestie, and remember: if it's way less than 1, the vibes are off 😭💅