DSYTRI2X(3)

💖 DSYTRI2X(3) 💖

okay bestie, welcome to the Library Functions Manual energy — this page is from the LAPACK crew, and we're about to make a Fortran inverse routine feel like main character material. ✨

🌸 NAME 🌸

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/dsytri2x.f

That's the full source path, bestie — long, specific, and not to be edited. 💅

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

subroutine DSYTRI2X (uplo, n, a, lda, ipiv, work, nb, info)

DSYTRI2X

🦋 Function/Subroutine Documentation 🦋

💫 DSYTRI2X 💫

subroutine DSYTRI2X (character uplo, integer n, double precision, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, double precision, dimension( n+nb+1,* ) work, integer nb, integer info)

DSYTRI2X

💅 Purpose

okay so DSYTRI2X 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 DSYTRF. That's the whole purpose, and it ate. 🔥

🎀 Parameters

💖 UPLO

UPLO is CHARACTER*1

Specifies 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

The order of the matrix A. N >= 0.

💖 A

A is DOUBLE PRECISION array, dimension (LDA,N)

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

On exit, if INFO = 0, 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

The leading dimension of the array A. LDA >= max(1,N).

💖 IPIV

IPIV is INTEGER array, dimension (N)

Details of the interchanges and the NNB structure of D as determined by DSYTRF.

💖 WORK

WORK is DOUBLE PRECISION array, dimension (N+NB+1,NB+3)

💖 NB

NB is INTEGER

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

Definition at line 119 of file dsytri2x.f.

🧚 Author

Generated automatically by Doxygen for LAPACK from the source code.

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byeee bestie 💖 this page's footer/source/version sign-off is LAPACK Version 3.12.0 and /home/abui.../dsytri2x.f(3) — that's the source/version/date footer situation, mwah. 🫶✨