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

📦 version 3.12.0, in opensuse-leap 16.0

hey bestie 💖 welcome to the /home/abui..._porcond.f(3) page — it lives in the Library Functions Manual, and it's giving “LAPACK routine that estimates a Skeel condition number” energy. no cap, we're gonna walk through every parameter, every constraint, and every little detail. 🫶

🌸 NAME 🌸

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

that's the file, bestie — the whole page is about this one Fortran source file.

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

  • real function SLA_PORCOND (uplo, n, a, lda, af, ldaf, cmode, c, info, work, iwork) — SLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix. slay.

🦋 Function/Subroutine Documentation 🦋

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

okay so this is the full signature, and yes it is a lot. SLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix. main character energy fr fr.

🔥 Purpose 🔥

SLA_PORCOND estimates the Skeel condition number of op(A) * op2(C), where op2 is determined by CMODE like this:

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

the Skeel condition number is cond(A) = norminf( |inv(A)||A| ), and it gets computed by computing scaling factors R such that diag(R)*A*op2(C) is row equilibrated, then computing the standard infinity-norm condition number. that's the whole vibe. 💅

💜 Parameters 💜

UPLO

UPLO is CHARACTER*1. 'U' means the upper triangle of A is stored; 'L' means the lower triangle of A is stored. pick your fave, but only those two, bestie.

N

N is INTEGER, and it's the number of linear equations, i.e. the order of the matrix A. constraint check: N >= 0. periodt.

A

A is a REAL array, dimension (LDA,N). on entry, it's the N-by-N matrix A. yup, she's the main character matrix.

LDA

LDA is INTEGER, the leading dimension of the array A. constraint: LDA >= max(1,N). don't fumble this one.

AF

AF is a REAL array, dimension (LDAF,N). it's the triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, as computed by SPOTRF. iconic Cholesky behavior.

LDAF

LDAF is INTEGER, the leading dimension of the array AF. constraint: LDAF >= max(1,N). same energy as LDA, but for AF.

CMODE

CMODE is INTEGER, and it determines op2(C) in the formula op(A) * op2(C) exactly like this:

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

it's giving “pick your op2 era” and we love that for us.

C

C is a REAL array, dimension (N). it's the vector C in the formula op(A) * op2(C). short, sweet, and very much part of the plot.

INFO

INFO is INTEGER. = 0: means successful exit. and then the literal line says i > 0: The ith argument is invalid. — so if that's showing up, check your args, bestie.

WORK

WORK is a REAL array, dimension (3*N). it's workspace. boring? maybe. necessary? absolutely. 💀

IWORK

IWORK is an INTEGER array, dimension (N). also workspace. we respect her.

🌈 Author 🌈

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

Definition at line 138 of file sla_porcond.f.

🎀 Author 🎀

Generated automatically by Doxygen for LAPACK from the source code.

and that's the whole page, bestie — xoxo, your LAPACK bestie 💖. the footer energy is LAPACK Version 3.12.0, and this page is /home/abui..._porcond.f(3). 🫶

📦 where this page comes from