SRC/dpttrs.f(3)

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📁 SRC/dpttrs.f(3) — Library Functions Manual 💅

okay bestie, welcome to the glow-up of SRC/dpttrs.f(3). This is the Library Functions Manual page for a very specific little LAPACK icon, and we are going to get into every detail. no skips. periodt. ✨

🌸 NAME 🌸

SRC/dpttrs.f — that's the name, bestie. iconic file, no cap. 🫶

✨ SYNOPSIS ✨

🎀 Functions/Subroutines 🎀

       subroutine dpttrs (n, nrhs, d, e, b, ldb, info)
           DPTTRS

🦋 Function/Subroutine Documentation 🦋

💫 subroutine dpttrs 💫

Here's the full signature in all its main-character glory:

   subroutine dpttrs (integer n, integer nrhs, double precision, dimension( * )
       d, double precision, dimension( * ) e, double precision, dimension( ldb,
       * ) b, integer ldb, integer info)

Label: DPTTRS. she's literally right there in the name. 💅

🎯 Purpose 🎯

DPTTRS solves a tridiagonal system of the form

A * X = B

using the L*D*L**T factorization of A computed by DPTTRF.

So picture this, bestie: D is a diagonal matrix specified in the vector D, L is a unit bidiagonal matrix whose subdiagonal is specified in the vector E, and X and B are N by NRHS matrices. that's the whole vibe. 🌈

💖 Parameters 💖

  • N — N is INTEGER; the order of the tridiagonal matrix A. N >= 0. 🫶
  • NRHS — NRHS is INTEGER; the number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. ✨
  • D — D is DOUBLE PRECISION array, dimension (N); the n diagonal elements of the diagonal matrix D from the L*D*L**T factorization of A. 💖
  • E — E is DOUBLE PRECISION array, dimension (N-1); the (n-1) subdiagonal elements of the unit bidiagonal factor L from the L*D*L**T factorization of A. E can also be regarded as the superdiagonal of the unit bidiagonal factor U from the factorization A = U**T*D*U. 🦋
  • B — B is DOUBLE PRECISION array, dimension (LDB,NRHS). On entry, the right hand side vectors B for the system of linear equations. On exit, the solution vectors, X. 💅
  • LDB — LDB is INTEGER; 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 👑

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

Definition at line 108 of file dpttrs.f.

🧚 Author 🧚

Generated automatically by Doxygen for LAPACK from the source code. ✨

okay that's the whole page, bestie 🫶 the footer says LAPACK, Version 3.12.0, and SRC/dpttrs.f(3) — no separate date listed in that footer line, just the version/source magic. bye 💋✨

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