SRC/spocon.f(3)

💅 SRC/spocon.f(3) 💅

okay so this is a page from the Library Functions Manual — manual name folded in right here, bestie, because we are not copying that header line like a robot. The title is SRC/spocon.f(3), and it's all about one little subroutine. periodt.

🌸 NAME 🌸

SRC/spocon.f — that's the name, short and iconic.

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

subroutine spocon (uplo, n, a, lda, anorm, rcond, work, iwork, info)
    SPOCON

🦋 Function/Subroutine Documentation 🦋

subroutine spocon (character uplo, integer n, real, dimension( lda, * ) a,
       integer lda, real anorm, real rcond, real, dimension( * ) work, integer,
       dimension( * ) iwork, integer info)

SPOCON is the main character here, and honestly? It ate.

🦋 Purpose 🦋

okay so what does it do? SPOCON estimates the reciprocal of the condition number (in the 1-norm) of a real symmetric positive definite matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPOTRF.

An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))). literally the whole vibe.

🎀 Parameters 🎀

here's the whole cast, no skips:

• UPLO — UPLO is CHARACTER*1. = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored. choose your triangle, bestie.
• N — N is INTEGER. The order of the matrix A. N >= 0.
• A — A is REAL array, dimension (LDA,N). The triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, as computed by SPOTRF.
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• ANORM — ANORM is REAL. The 1-norm (or infinity-norm) of the symmetric matrix A.
• RCOND — RCOND is REAL. The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an estimate of the 1-norm of inv(A) computed in this routine.
• WORK — WORK is REAL array, dimension (3*N).
• IWORK — IWORK is INTEGER array, dimension (N).
• INFO — INFO is INTEGER:
  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value

vibe check note: if INFO = -i, that means the i-th argument had an illegal value — no cap, that's the error.

💖 Author 💖

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

📌 Definition at line 119 of file spocon.f. 📌

that's the exact line, bestie — no edits.

🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code. — iconic automation behavior, honestly.

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💖 that's the whole SRC/spocon.f(3) page, bestie! 💖 footer vibe: LAPACK Version 3.12.0 and SRC/spocon.f(3) — and there's no separate date in the footer, so I'm not inventing one. periodt. 🫶