SRC/dpotf2.f(3)

💅 SRC/dpotf2.f(3) 💅

okay bestie, this is SRC/dpotf2.f(3) from the Library Functions Manual, and it is literally the page for dpotf2. Cholesky factorization? yes ma'am. unblocked algorithm? also yes. no cap. 💖

✨ NAME ✨

SRC/dpotf2.f

🌸 SYNOPSIS 🌸

🎀 Functions/Subroutines 🎀

• subroutine dpotf2 (uplo, n, a, lda, info) — DPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

🦋 Function/Subroutine Documentation 🦋

🧚 subroutine dpotf2 (uplo, n, a, lda, info) 🧚

subroutine dpotf2 (character uplo, integer n, double precision, dimension(
       lda, * ) a, integer lda, integer info)

DPOTF2 computes the Cholesky factorization of a symmetric/Hermitian positive definite matrix (unblocked algorithm).

✨ Purpose ✨

okay so here's the tea: DPOTF2 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. iconic behavior. 💅

🌈 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 DOUBLE PRECISION 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 dpotf2.f.

🤖 Author 🤖

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