SRC/zpotri.f(3)

📦
version 3.12.1 · 7 versions
, in arch rolling

💖 NAME 💖

okay so this page is literally SRC/zpotri.f(3) from the Library Functions Manual, and its NAME section is just SRC/zpotri.f — no extra subtitle, bestie. It's the LAPACK page for the ZPOTRI subroutine, and it's lowkey iconic. ✨

🛠️ SYNOPSIS 🛠️

Functions/Subroutines

subroutine zpotri (uplo, n, a, lda, info)
    ZPOTRI

🧚 Function/Subroutine Documentation 🧚

subroutine zpotri (character uplo, integer n, complex*16, dimension( lda, * ) a, integer lda, integer info)
    ZPOTRI

🎯 Purpose 🎯

Bestie, ZPOTRI computes the inverse of a complex Hermitian positive definite matrix A using the Cholesky factorization A = U**H*U or A = L*L**H computed by ZPOTRF. That's the whole assignment, and it ate. 💅

🎀 Parameters 🎀

💌 UPLO 💌

UPLO is CHARACTER*1 — it's the little flag that says which triangle of A is stored:

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

🦋 N 🦋

N is INTEGER — the order of the matrix A. It must satisfy N >= 0. No negative chaos allowed, bestie. ✨

🍓 A 🍓

A is a COMPLEX*16 array, dimension (LDA,N).

On entry, it's the triangular factor U or L from the Cholesky factorization A = U**H*U or A = L*L**H, as computed by ZPOTRF.

On exit, it holds the upper or lower triangle of the (Hermitian) inverse of A, overwriting the input factor U or L. So it's giving "come in with a factor, leave with an inverse." 💀

🌸 LDA 🌸

LDA is INTEGER — the leading dimension of the array A. It must satisfy LDA >= max(1,N). Respect the leading dimension. 🫶

🔥 INFO 🔥

INFO is INTEGER, and it's the post-call vibe check:

  • = 0: successful exit;
  • < 0: if INFO = -i, the i-th argument had an illegal value;
  • > 0: if INFO = i, the (i,i) element of the factor U or L is zero, and the inverse could not be computed.
Warning-ish energy: if INFO comes back positive, the inverse did not happen — the factor had a zero on the diagonal, and the inverse could not be computed. 😭

👑 Author 👑

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

📌 Definition at line 94 of file zpotri.f.

🌈 Author 🌈

Generated automatically by Doxygen for LAPACK from the source code.

okay bestie, that's the whole page. The footer vibe is LAPACK Version 3.12.0, file SRC/zpotri.f(3) — and the original footer doesn't list a separate date, so I'm not inventing one. bye, slay, mwah 💋✨

📦 where this page comes from