CTRTRI(3)

📦 version 3.12.0, in opensuse-leap 16.0

💖 ctrtri.f(3) — Library Functions Manual 💖

Okay bestie, welcome to the glow-up of the Library Functions Manual page for ctrtri.f(3). It's giving "linear algebra but make it cute" and I'm obsessed.

🌸 NAME 🌸

This page is about this exact file, no cap:

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

✨ SYNOPSIS ✨

Functions/Subroutines

subroutine CTRTRI (uplo, diag, n, a, lda, info)
    CTRTRI

🦋 Function/Subroutine Documentation 🦋

subroutine CTRTRI signature, fr fr

subroutine CTRTRI (character uplo, character diag, integer n, complex,
    dimension( lda, * ) a, integer lda, integer info)

CTRTRI

🎀 Purpose 🎀

So, CTRTRI computes the inverse of a complex upper or lower triangular matrix A. It's literally "undo the triangle" energy. This is the Level 3 BLAS version of the algorithm. Periodt. 💅

💅 Parameters 💅

UPLO

UPLO is CHARACTER*1, and it tells us which triangle we're working with:

  • = 'U': A is upper triangular;
  • = 'L': A is lower triangular.

DIAG

DIAG is CHARACTER*1, and it's the unit-or-not situation:

  • = 'N': A is non-unit triangular;
  • = 'U': A is unit triangular.

N

N is INTEGER. It's the order of the matrix A. Constraint: N >= 0.

A

A is COMPLEX array, dimension (LDA,N). On entry, it's the triangular matrix A, and the storage rules are lowkey specific:

  • If UPLO = 'U', the leading N-by-N upper triangular part of the array A contains the upper triangular matrix, and the strictly lower triangular part of A is not referenced.
  • If UPLO = 'L', the leading N-by-N lower triangular part of the array A contains the lower triangular matrix, and the strictly upper triangular part of A is not referenced.
  • If DIAG = 'U', the diagonal elements of A are also not referenced and are assumed to be 1.

On exit, A holds the (triangular) inverse of the original matrix, in the same storage format. Iconic. ✨

LDA

LDA is INTEGER. It's the leading dimension of the array A. Constraint: LDA >= max(1,N).

INFO

INFO is INTEGER, and the vibes are:

  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value
  • > 0: if INFO = i, A(i,i) is exactly zero. The triangular matrix is singular and its inverse can not be computed.
Bestie, that last one is the "uh oh" case — singular matrix, no inverse, no slay. 💀

🌈 Author 🌈

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

Definition at line 108 of file ctrtri.f.

⭐ Author ⭐

This one's the auto-generated bit:

Generated automatically by Doxygen for LAPACK from the source code.

Okay bestie, that's the whole page. Final sign-off energy: this is LAPACK, Version 3.12.0, with the footer path /home/abui...RC/ctrtri.f(3). Mwah 💋✨🫶

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