/home/abui.../dpotrf2.f(3)

🎀 NAME 🎀

okay so this is the dpotrf2.f(3) page from the Library Functions Manual, and the header path vibe is /home/abui.../dpotrf2.f(3). The actual source file being documented is:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dpotrf2.f

— periodt. 💅

✨ SYNOPSIS ✨

Functions/Subroutines

recursive subroutine DPOTRF2 (uplo, n, a, lda, info)
    DPOTRF2

💖 Function/Subroutine Documentation 💖

okay bestie, here's the main character signature:

recursive subroutine DPOTRF2 (character uplo, integer n, double precision,
    dimension( lda, * ) a, integer lda, integer info)

DPOTRF2 is literally the icon. 🫶

🧠 Purpose 🧠

DPOTRF2 computes the Cholesky factorization of a real symmetric positive definite matrix A using the recursive algorithm. No cap.

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 recursive version of the algorithm. It divides the matrix into four submatrices:

       [  A11 | A12  ]  where A11 is n1 by n1 and A22 is n2 by n2
   A = [ -----|----- ]  with n1 = n/2
       [  A21 | A22  ]       n2 = n-n1

The subroutine calls itself to factor A11. Then it updates and scales A21 or A12, updates A22, and then calls itself to factor A22. Recursion ate, honestly. 🔥

🌸 Parameters 🌸

• UPLO — is CHARACTER*1. = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.
• N — is INTEGER. The order of the matrix A. N >= 0.
• 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 — is INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• 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.

👑 Author 👑

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

Definition at line 105 of file dpotrf2.f.

👑 Author 👑

Generated automatically by Doxygen for LAPACK from the source code.

---

okay that's the whole page, bestie 💖 — source is LAPACK, Version 3.12.0, and the footer path is /home/abui.../dpotrf2.f(3). There's no date on this footer, so no invented date, fr fr. Byeee 🫶✨