CHETRI2X(3)

🌸 NAME 🌸

Bestie, this is CHETRI2X(3) from the Library Functions Manual, and the header points at /home/abui.../chetri2x.f(3). The NAME line is literally:

/home/abuild/rpmbuild/BUILD/lapack-static-3.12.0-build/lapack-3.12.0/SRC/chetri2x.f

So yeah, it’s giving “source file main character energy” 💅✨.

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✨ SYNOPSIS ✨

💅 Functions/Subroutines 💅

subroutine CHETRI2X (uplo, n, a, lda, ipiv, work, nb, info)

CHETRI2X

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🦋 Function/Subroutine Documentation 🦋

subroutine CHETRI2X (character uplo, integer n, complex, dimension( lda, * )
       a, integer lda, integer, dimension( * ) ipiv, complex, dimension(
       n+nb+1,* ) work, integer nb, integer info)

CHETRI2X

🌈 Purpose 🌈

Okay so CHETRI2X computes the inverse of a complex Hermitian indefinite matrix A using the factorization A = U*D*U**H or A = L*D*L**H computed by CHETRF. That’s the whole vibe, no cap 💖.

🍓 Parameters 🍓

• 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**H;
  • 'L': Lower triangular, form is A = L*D*L**H.
• N — is INTEGER. The order of the matrix A. N >= 0 ✨.
• A — is COMPLEX 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 CHETRF.

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. Slay, triangular storage 💅.

• LDA — is INTEGER. The leading dimension of the array A. LDA >= max(1,N).
• IPIV — is INTEGER array, dimension (N). Details of the interchanges and the NNB structure of D as determined by CHETRF.
• WORK — is COMPLEX array, dimension (N+NB+1,NB+3).
• NB — is INTEGER. Block size.
• 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.

⚠️ Bestie, if INFO > 0, the matrix is singular and D(i,i) = 0, so the inverse could not be computed. That’s not a vibe 😭.

👑 Author 👑

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

Definition at line 119 of file chetri2x.f.

🎀 Author 🎀

Generated automatically by Doxygen for LAPACK from the source code.

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💖 Cute sign-off: LAPACK Version 3.12.0, source path /home/abui.../chetri2x.f(3) — the footer has no date field, just that version/path energy. Periodt. 🫶✨