SRC/spotri.f(3)

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✨ SRC/spotri.f(3) — Library Functions Manual ✨

okay so bestie, welcome to the SRC/spotri.f page 💅 the manual name is literally Library Functions Manual, and we're folding that in right here at the top instead of making you read a whole header line. You're welcome. 🎀

🎀 NAME 🎀

SRC/spotri.f

That's it. That's the name. iconic, honestly. ✨

🌸 SYNOPSIS 🌸

Functions/Subroutines

subroutine spotri (uplo, n, a, lda, info)
    SPOTRI

The function/subroutine section is giving main character energy: SPOTRI is the one we're talking about. 🫶

💜 Function/Subroutine Documentation 💜

subroutine spotri (character uplo, integer n, real, dimension( lda, * ) a, integer lda, integer info)

SPOTRI — okay, this is the whole vibe. 🦋

Purpose

SPOTRI computes the inverse of a real symmetric positive definite matrix A using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPOTRF. So: Cholesky factor goes in, inverse comes out. slay. ✨

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 REAL array, dimension (LDA,N)
    • On entry, the triangular factor U or L from the Cholesky factorization A = U**T*U or A = L*L**T, as computed by SPOTRF.
    • On exit, the upper or lower triangle of the (symmetric) inverse of A, overwriting the input factor U or L.
  • 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 (i,i) element of the factor U or L is zero, and the inverse could not be computed.
heads up bestie: if INFO > 0, the inverse literally could not be computed because the (i,i) element of the factor U or L is zero. not a slay, but at least you know why. 💀

Author

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

Definition at line 94 of file spotri.f.

Author

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okay bestie, final footer sign-off: source/version is LAPACK Version 3.12.0, page is SRC/spotri.f(3), and there's no date printed on this footer — so no invented dates, periodt. 💖✨

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