/home/abui..._syrcond.f(3)

💅 /home/abui..._syrcond.f 💅

okay bestie, so this is a page from the LAPACK Library Functions Manual and it's all about one little overachiever of a Fortran function, no cap ✨

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🎀 NAME 🎀

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/sla_syrcond.f

like. that's the whole name. she's literally a file path and she owns it 💅

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✨ SYNOPSIS ✨

Functions/Subroutines

• real function SLA_SYRCOND (uplo, n, a, lda, af, ldaf, ipiv, cmode, c, info, work, iwork) — SLA_SYRCOND estimates the Skeel condition number for a symmetric indefinite matrix. iconic behavior honestly 🫶

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🦋 Function/Subroutine Documentation 🦋

real function SLA_SYRCOND (character uplo, integer n, real, dimension( lda, * ) a, integer lda, real, dimension( ldaf, * ) af, integer ldaf, integer, dimension( * ) ipiv, integer cmode, real, dimension( * ) c, integer info, real, dimension( * ) work, integer, dimension( * ) iwork)

SLA_SYRCOND estimates the Skeel condition number for a symmetric indefinite matrix. that's her whole job and she does it flawlessly 💖

Purpose

so here's the tea 🍓 — SLA_SYRCOND estimates the Skeel condition number of op(A) * op2(C), where op2 is decided by CMODE, like this:

CMODE =  1    op2(C) = C
CMODE =  0    op2(C) = I
CMODE = -1    op2(C) = inv(C)

and the Skeel condition number itself is this whole moment:

cond(A) = norminf( |inv(A)||A| )

it gets computed by finding scaling factors R such that diag(R)*A*op2(C) is row equilibrated, and then computing the standard infinity-norm condition number. math queen behavior fr fr 👑

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🌸 Parameters 🌸

UPLO

UPLO is CHARACTER*1

• = 'U': Upper triangle of A is stored;
• = 'L': Lower triangle of A is stored.

pick your triangle, bestie, there's only two 💅

N

N is INTEGER

the number of linear equations, i.e., the order of the matrix A. N >= 0. no negative vibes allowed 🙈

A

A is REAL array, dimension (LDA,N)

on entry, the N-by-N matrix A. that's the main character right there ⭐

LDA

LDA is INTEGER

the leading dimension of the array A. LDA >= max(1,N). respect the constraint or else 😭

AF

AF is REAL array, dimension (LDAF,N)

the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by SSYTRF. she's already been through the factorization pipeline 🧚

LDAF

LDAF is INTEGER

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

IPIV

IPIV is INTEGER array, dimension (N)

details of the interchanges and the block structure of D as determined by SSYTRF. the receipts of what got swapped where 🔥

CMODE

CMODE is INTEGER

determines op2(C) in the formula op(A) * op2(C) as follows:

CMODE =  1    op2(C) = C
CMODE =  0    op2(C) = I
CMODE = -1    op2(C) = inv(C)

C

C is REAL array, dimension (N)

the vector C in the formula op(A) * op2(C). yes she gets a whole letter, she earned it 💜

INFO

INFO is INTEGER

• = 0: Successful exit.
• i > 0: The ith argument is invalid.

🚨 heads up — if INFO comes back positive, that's not a slay, that means an argument was invalid. go check your inputs bestie 😭

WORK

WORK is REAL array, dimension (3*N).

Workspace.

IWORK

IWORK is INTEGER array, dimension (N).

Workspace.

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👑 Author 👑

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

Definition at line 144 of file sla_syrcond.f. go look, she's literally right there 💅

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🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code. not a human, just a little robot doing its thing 🤖✨

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💖 and that's the whole page bestie!! every flag, every array, every constraint, all of it, untouched 💖

LAPACK, Version 3.12.0 — this page was /home/abui..._syrcond.f(3), and it ate, no crumbs, periodt 🎀🌸🦋