ZPTTRF(3)

💖 NAME 💖

okay so welcome to the zpttrf.f(3) page from the Library Functions Manual, bestie 💅 this one is literally a file path in the NAME section:

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

yes, the NAME line is giving “I am the source file” energy, and honestly? iconic 🫶

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✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

• subroutine ZPTTRF (n, d, e, info) — ZPTTRF

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💅 Function/Subroutine Documentation 💅

subroutine ZPTTRF (integer n, double precision, dimension( * ) d,
       complex*16, dimension( * ) e, integer info)

ZPTTRF is the main character here 👑

🎀 Purpose 🎀

ZPTTRF computes the L*D*L**H factorization of a complex Hermitian positive definite tridiagonal matrix A. The factorization may also be regarded as having the form A = U**H *D*U. periodt ✨

🍓 Parameters 🍓

🦋 N 🦋

N is INTEGER.

The order of the matrix A. N >= 0.

🦋 D 🦋

D is DOUBLE PRECISION array, dimension (N).

On entry, the n diagonal elements of the tridiagonal matrix A. On exit, the n diagonal elements of the diagonal matrix D from the L*D*L**H factorization of A. slay 💫

🦋 E 🦋

E is COMPLEX*16 array, dimension (N-1).

On entry, the (n-1) subdiagonal elements of the tridiagonal matrix A. On exit, the (n-1) subdiagonal elements of the unit bidiagonal factor L from the L*D*L**H factorization of A.

E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the U**H *D*U factorization of A. it’s giving dual-purpose, iykyk 🦋

🦋 INFO 🦋

INFO is INTEGER.

• = 0: successful exit 🌸
• < 0: if INFO = -k, the k-th argument had an illegal value 🙈
• > 0: if INFO = k, the leading principal minor of order k is not positive; if k < N, the factorization could not be completed, while if k = N, the factorization was completed, but D(N) <= 0.

bestie, INFO > 0 is the “vibe check failed” signal: a leading principal minor is not positive. no cap 😭

👑 Author 👑

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

📌 Definition at line 91 of file zpttrf.f. 📌

🫶 Author 🫶

Generated automatically by Doxygen for LAPACK from the source code.

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LAPACK, Version 3.12.0 — signed off from /home/abui...RC/zpttrf.f(3) 💖✨ that’s the whole footer vibe, bestie 🫶