SRC/zsytri.f(3)

Hey bestie 💖 welcome to SRC/zsytri.f(3) from the Library Functions Manual — this page is all about the ZSYTRI routine and it's giving major linear-algebra main character energy. ✨

🎀 NAME 🎀

SRC/zsytri.f — that's the name, bestie. Short, iconic, source-file realness. 💅

✨ SYNOPSIS ✨

✨ Functions/Subroutines ✨

• subroutine zsytri (uplo, n, a, lda, ipiv, work, info) — the callable, and the routine name is ZSYTRI.

💖 Function/Subroutine Documentation 💖

Here's the full signature, exactly as the page gives it:

   subroutine zsytri (character uplo, integer n, complex*16, dimension( lda, *
       ) a, integer lda, integer, dimension( * ) ipiv, complex*16, dimension( *
       ) work, integer info)

ZSYTRI

🎯 Purpose 🎯

ZSYTRI 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. No cap, that's the whole glow-up. 🌸

💅 Parameters 💅

• UPLO — it's 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 — it's INTEGER. The order of the matrix A. N >= 0. ⭐
• A — it's COMPLEX*16 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 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. That part is important, bestie — don't go reading the triangle that isn't referenced. 🎀

• LDA — it's INTEGER. The leading dimension of the array A. LDA >= max(1,N). 💫
• IPIV — it's INTEGER array, dimension (N). Details of the interchanges and the block structure of D as determined by ZSYTRF. 🧚
• WORK — it's COMPLEX*16 array, dimension (2*N). 🫶
• INFO — it's 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. Translation: if that last one happens, the inverse is not coming to the function. Periodt. 💀

👑 Author 👑

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

Definition at line 113 of file zsytri.f.

🌟 Author 🌟

Generated automatically by Doxygen for LAPACK from the source code.

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