SRC/chetri2.f(3)

💖 SRC/chetri2.f(3) 💖

okay so welcome to the Library Functions Manual page for SRC/chetri2.f — yes bestie, this is the one. It's giving “LAPACK subroutine documentation but make it group-chat.” No cap, every flag and fact is staying right here. 💅

✨ NAME ✨

SRC/chetri2.f — that's the name, periodt.

✨ SYNOPSIS ✨

🫶 Functions/Subroutines 🫶

• subroutine chetri2 (uplo, n, a, lda, ipiv, work, lwork, info) — CHETRI2

🫶 Function/Subroutine Documentation 🫶

subroutine chetri2 (character uplo, integer n, complex, dimension( lda, * )
a, integer lda, integer, dimension( * ) ipiv, complex, dimension( * )
work, integer lwork, integer info)

This one is CHETRI2, bestie. Iconic.

🎯 Purpose 🎯

okay so CHETRI2 computes the inverse of a COMPLEX hermitian indefinite matrix A using the factorization A = U*D*U**T or A = L*D*L**T computed by CHETRF. CHETRI2 set the LEADING DIMENSION of the workspace before calling CHETRI2X that actually computes the inverse.

🧚 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 array, dimension (LDA,N). On entry, the block 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.

🎀 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 block structure of D as determined by CHETRF.

🔥 WORK

WORK is COMPLEX array, dimension (MAX(1,LWORK)).

💜 LWORK

LWORK is INTEGER. The dimension of the array WORK. If N = 0, LWORK >= 1, else LWORK >= (N+NB+1)*(NB+3). If LWORK = -1, then a workspace query is assumed; the routine calculates:

• the optimal size of the WORK array, returns this value as the first entry of the WORK array,
• and no error message related to LWORK is issued by XERBLA.

🌈 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 126 of file chetri2.f.

🌸 Author 🌸

Generated automatically by Doxygen for LAPACK from the source code.

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