ZSYTRI2X(3)

📦 version 3.12.0, in opensuse-leap 16.0

💅 ZSYTRI2X(3) 💅

okay so bestie, we are in the LAPACK Library Functions Manual and this page is all about ZSYTRI2X. It's giving Fortran, it's giving factorization, and it's honestly iconic. ✨

✨ NAME ✨

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/zsytri2x.f — literally the source file for ZSYTRI2X. That's the whole NAME section, no cap. 💅

🌸 SYNOPSIS 🌸

Functions/Subroutines

subroutine ZSYTRI2X (uplo, n, a, lda, ipiv, work, nb, info)

ZSYTRI2X — that's the main character.

🎀 Function/Subroutine Documentation 🎀

subroutine ZSYTRI2X (character uplo, integer n, complex*16, dimension( lda,
* ) a, integer lda, integer, dimension( * ) ipiv, complex*16, dimension(
n+nb+1,* ) work, integer nb, integer info)

ZSYTRI2X

Purpose

The source has all those !> Doxygen comment markers, but the actual tea is this:

ZSYTRI2X computes the inverse of a complex symmetric indefinite matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by ZSYTRF.

Parameters

UPLO

UPLO is CHARACTER*1.

It 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 COMPLEX*16 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 ZSYTRF.

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 ZSYTRF.

WORK

WORK is COMPLEX*16 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 at line 119 of file zsytri2x.f.

✨ Author ✨

Generated automatically by Doxygen for LAPACK from the source code.

okay that's the whole page, bestie. Cute little sign-off: LAPACK Version 3.12.0 and the footer path /home/abui.../zsytri2x.f(3). There's no date on this footer, just those two, so don't come for me. 💖✨

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