SRC/dpotrf.f(3)

🌸 SRC/dpotrf.f(3) 🌸

Ok bestie, welcome to the SRC/dpotrf.f(3) page from the Library Functions Manual 💖. This is the DPOTRF zone, and it's giving Fortran linear algebra main character energy. Let's go. ✨

✨ NAME ✨

SRC/dpotrf.f

That's literally the page/file name, periodt. 🎀

🦋 SYNOPSIS 🦋

Functions/Subroutines

• subroutine dpotrf (uplo, n, a, lda, info) — DPOTRF. Yep, that's the subroutine and its argument list, exactly as listed. Slay. 💅

💖 Function/Subroutine Documentation 💖

🧚 Subroutine Signature 🧚

subroutine dpotrf (character uplo, integer n, double precision, dimension(
       lda, * ) a, integer lda, integer info)

DPOTRF — iconic, no notes.

🎀 Purpose 🎀

DPOTRF computes the Cholesky factorization of a real symmetric positive definite matrix A. That's the assignment, bestie. 💖

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. The way that this triangular setup is written out? Obsessed, ngl. 🌸

This is the block version of the algorithm, calling Level 3 BLAS. So yes, it's the block-y one — highkey important detail. This block version ate, honestly. 🔥

🫶 Parameters 🫶

All the parameter specs are below, no cap. 🫶

UPLO

UPLO is CHARACTER*1

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

N

N is INTEGER

The order of the matrix A. N >= 0.

A

A is DOUBLE PRECISION 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. LDA >= max(1,N). Lowkey a dimension rule, but make sure it's satisfied. 🦋

INFO

INFO is INTEGER

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

That's the exit/vibe check, fr fr. 💜

👑 Author 👑

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

Definition at line 106 of file dpotrf.f.

🌈 Author (auto-generated) 🌈

Generated automatically by Doxygen for LAPACK from the source code.

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Cute sign-off from the footer: LAPACK, Version 3.12.0, and SRC/dpotrf.f(3) 💖. That's the source/version footer info — no separate date line in this copy, fr fr. ✨