SRC/spotf2.f(3)

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version 3.12.1 · 7 versions
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🌟 NAME 🌟

okay so welcome to the SRC/spotf2.f(3) page from the Library Functions Manual — the NAME here is literally SRC/spotf2.f, and this whole page is about the spotf2 routine. bestie, it’s giving linear algebra main character energy. 💅

✨ SYNOPSIS ✨

🌸 Functions/Subroutines 🌸

  • subroutine spotf2 (uplo, n, a, lda, info) — SPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

🦋 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 ✨

ok so the source says, and I quote the important bits: 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. slay.

🎀 Parameters 🎀

  • UPLO — UPLO is CHARACTER*1. 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. Constraint: N >= 0.
  • A — A is REAL array, dimension (LDA,N). On entry, 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. Constraint: 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 🎀

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and that’s the whole page, bestie. Footer sign-off: LAPACK Version 3.12.0, SRC/spotf2.f(3) — mwah 💋✨

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