SPOTF2(3)

okay so bestie, this is spotf2.f(3) from the Library Functions Manual — and no cap, it’s the unblocked Cholesky girlie for real symmetric positive definite matrices. Let’s get into it. 🫶

💖 NAME 💖

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/spotf2.f

That whole path is the name here, bestie. It’s the source file for this routine. ✨

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🌈 SYNOPSIS 🌈

Functions/Subroutines

subroutine SPOTF2 (uplo, n, a, lda, info)

SPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

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🦋 Function/Subroutine Documentation 🦋

subroutine SPOTF2 (character uplo, integer n, real, dimension( lda, * ) a,
    integer lda, integer info)

SPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

✨ Purpose ✨

SPOTF2 computes the Cholesky factorization of a real symmetric positive definite matrix A. 🫶

The factorization has the form:

A = U**T * U ,  if UPLO = 'U', or
A = L  * L**T,  if UPLO = 'L',

where U is an upper triangular matrix and L is lower triangular. 💅

This is the unblocked version of the algorithm, calling Level 2 BLAS. no cap.

🎀 Parameters 🎀

UPLO

• UPLO is CHARACTER*1 — it specifies whether the upper or lower triangular part of the symmetric matrix A is stored.
  • = 'U' — Upper triangular
  • = 'L' — Lower triangular

N

• N is INTEGER — the order of the matrix A. N >= 0.

A

• A is REAL array, dimension (LDA,N).
• On entry, it’s the symmetric matrix A. If UPLO = 'U', the leading n by n upper triangular part of A contains the upper triangular part of the matrix A, and the strictly lower triangular part of A is not referenced. If UPLO = 'L', the leading n by n lower triangular part of A contains the lower triangular part of the matrix A, and the strictly upper triangular part of A is not referenced. 🙈
• On exit, if INFO = 0, the factor U or L from the Cholesky factorization A = U**T *U or A = L*L**T.

LDA

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

INFO

• INFO is INTEGER.
  • = 0 — successful exit
  • < 0 — if INFO = -k, the k-th argument had an illegal value
  • > 0 — if INFO = k, the leading principal minor of order k is not positive, and the factorization could not be completed.

💜 Author 💜

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

Definition at line 108 of file spotf2.f.

🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code.

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🫶 cute sign-off: source/version is LAPACK Version 3.12.0, and the footer path is /home/abui...RC/spotf2.f(3). Bye bestie, slay your Cholesky! 💅✨