SRC/csytri2.f(3)

SRC/csytri2.f(3) 💅

Okay so this is the Library Functions Manual page for SRC/csytri2.f(3) — yes bestie, the manual name is folded in right here, no need to copy the whole header line. ✨

✨ NAME ✨

SRC/csytri2.f — that's the name, that's the whole vibe. 🎀

🦋 SYNOPSIS 🦋

Functions/Subroutines

subroutine csytri2 (uplo, n, a, lda, ipiv, work, lwork, info)

CSYTRI2

💅 Function/Subroutine Documentation 💅

subroutine csytri2 (character uplo, integer n, complex, dimension( lda, * ) a, integer lda, integer, dimension( * ) ipiv, complex, dimension( * ) work, integer lwork, integer info)

CSYTRI2

Purpose

CSYTRI2 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 CSYTRF. It sets the LEADING DIMENSION of the workspace before calling CSYTRI2X, and CSYTRI2X is the one that actually computes the inverse. No cap, that's the job. 🫶

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, it's the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by CSYTRF. 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. Iconic triangular behavior, honestly. 🦋
• LDA — LDA is INTEGER. The leading dimension of the array A. LDA >= max(1,N). Periodt.
• IPIV — IPIV is INTEGER array, dimension (N). Details of the interchanges and the block structure of D as determined by CSYTRF.
• WORK — WORK is COMPLEX array, dimension (N+NB+1)*(NB+3).
• LWORK — LWORK is INTEGER. The dimension of the array WORK. WORK is size >= (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. 😭 That's the danger zone, bestie.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 126 of file csytri2.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

---

Cute sign-off: this page is LAPACK Version 3.12.0, source SRC/csytri2.f(3). The footer has no extra date to report, so I'm not making one up — slay responsibly. 💅✨