SRC/ssytri2x.f(3)

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hey bestie!! this is the SRC/ssytri2x.f(3) page from the Library Functions Manual, and we're diving into SSYTRI2X 💅✨

🎀 NAME 🎀

SRC/ssytri2x.f

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

subroutine ssytri2x (uplo, n, a, lda, ipiv, work, nb, info)
    SSYTRI2X

🦋 Function/Subroutine Documentation 🦋

subroutine ssytri2x (character uplo, integer n, real, dimension( lda, * ) a,
    integer lda, integer, dimension( * ) ipiv, real, dimension( n+nb+1,* )
    work, integer nb, integer info)
    SSYTRI2X

💖 Purpose 💖

okay so SSYTRI2X computes the inverse of a real symmetric indefinite matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by SSYTRF. that's the whole vibe 🫶

🌸 Parameters 🌸

💅 UPLO

UPLO is CHARACTER*1. it says whether the details of the factorization are stored as an upper or lower triangular matrix.

  • = 'U': Upper triangular, form is A = U*D*U**T;
  • = 'L': Lower triangular, form is A = L*D*L**T.

🍓 N

N is INTEGER. it's the order of the matrix A. N >= 0.

🎀 A

A is REAL array, dimension (LDA,N).

On entry, it's the NNB diagonal matrix D and the multipliers used to obtain the factor U or L as computed by SSYTRF.

On exit, if INFO = 0, it's the (symmetric) inverse of the original matrix. If UPLO = 'U', the upper triangular part of the inverse is formed and the part of A below the diagonal is not referenced; if UPLO = 'L', the lower triangular part of the inverse is formed and the part of A above the diagonal is not referenced.

🦋 LDA

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

⭐ IPIV

IPIV is INTEGER array, dimension (N). it holds details of the interchanges and the NNB structure of D as determined by SSYTRF.

🌈 WORK

WORK is REAL array, dimension (N+NB+1,NB+3).

👑 NB

NB is INTEGER. it's the block size.

🔥 INFO

INFO is INTEGER.

  • = 0: successful exit
  • < 0: if INFO = -i, the i-th argument had an illegal value
  • > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its inverse could not be computed.

💜 Author 💜

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 119 of file ssytri2x.f.

💫 Author 💫

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k bye bestie!! this page is from LAPACK Version 3.12.0, page SRC/ssytri2x.f(3) — generated automatically by Doxygen for LAPACK from the source code. 🫶✨💅

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