SRC/zpttrs.f(3)

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version 3.12.1 · 7 versions
, in arch rolling

okay so bestie, this is SRC/zpttrs.f(3), straight out of the Library Functions Manual. It’s the ZPTTRS page, and we are keeping every single detail — the vibes are immaculate, the facts are untouched. periodt. 💅

🌸 NAME 🌸

SRC/zpttrs.f

✨ SYNOPSIS ✨

🧚 Functions/Subroutines 🧚

  • subroutine zpttrs (uplo, n, nrhs, d, e, b, ldb, info) — the main-character subroutine, aka ZPTTRS 🫶
       subroutine zpttrs (uplo, n, nrhs, d, e, b, ldb, info)
           ZPTTRS

🦋 Function/Subroutine Documentation 🦋

okay here’s the full signature, and yes it’s giving “I know exactly what I’m doing” energy:

   subroutine zpttrs (character uplo, integer n, integer nrhs, double
       precision, dimension( * ) d, complex*16, dimension( * ) e, complex*16,
       dimension( ldb, * ) b, integer ldb, integer info)
       ZPTTRS

🎀 Purpose 🎀

ZPTTRS solves a tridiagonal system of the form

A * X = B

using the factorization A = U**H *D* U or A = L*D*L**H computed by ZPTTRF. D is a diagonal matrix specified in the vector D; U (or L) is a unit bidiagonal matrix whose superdiagonal (subdiagonal) is specified in the vector E; and X and B are N by NRHS matrices. 💖

💅 Parameters 💅

  • UPLO — UPLO is CHARACTER*1. It specifies the form of the factorization and whether the vector E is the superdiagonal of the upper bidiagonal factor U or the subdiagonal of the lower bidiagonal factor L. = 'U': A = U**H *D*U, and E is the superdiagonal of U. = 'L': A = L*D*L**H, and E is the subdiagonal of L. ✨
  • N — N is INTEGER. It’s the order of the tridiagonal matrix A. N >= 0. 🎀
  • NRHS — NRHS is INTEGER. It’s the number of right hand sides, i.e. the number of columns of the matrix B. NRHS >= 0. 🦋
  • D — D is a DOUBLE PRECISION array, dimension (N). These are the n diagonal elements of the diagonal matrix D from the factorization A = U**H *D*U or A = L*D*L**H. 🌸
  • E — E is a COMPLEX*16 array, dimension (N-1). If UPLO = 'U', it holds the (n-1) superdiagonal elements of the unit bidiagonal factor U from the factorization A = U**H*D*U. If UPLO = 'L', it holds the (n-1) subdiagonal elements of the unit bidiagonal factor L from the factorization A = L*D*L**H. 💫
  • B — B is a COMPLEX*16 array, dimension (LDB,NRHS). On entry, it’s the right hand side vectors B for the system of linear equations. On exit, it’s the solution vectors, X. 👑
  • LDB — LDB is INTEGER. It’s the leading dimension of the array B. LDB >= max(1,N). 🫶
  • INFO — INFO is INTEGER. = 0: successful exit. < 0: if INFO = -k, the k-th argument had an illegal value. 🚨

💖 Author 💖

the certified geniuses behind this baddie:

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

Definition at line 120 of file zpttrs.f.

🌟 Author 🌟

and the official generated-credit line says: Generated automatically by Doxygen for LAPACK from the source code. 😌✨

mwah 💋 — this footer cutie is LAPACK Version 3.12.0, page SRC/zpttrs.f(3). that’s the version and page, bestie; no cap, we made it. 🌈💖

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