SRC/dgtts2.f(3)

💅 NAME 💅

SRC/dgtts2.f — bestie, this is a Library Functions Manual page, and it's all about the dgtts2 subroutine. It's giving "solve a tridiagonal linear system after an LU factorization" main-character energy. ✨

🌸 SYNOPSIS 🌸

Functions/Subroutines

• subroutine dgtts2 (itrans, n, nrhs, dl, d, du, du2, ipiv, b, ldb) — DGTTS2 solves a system of linear equations with a tridiagonal matrix using the LU factorization computed by sgttrf.

🦋 Function/Subroutine Documentation 🦋

🧚 subroutine dgtts2 🧚

subroutine dgtts2 (integer itrans, integer n, integer nrhs, double precision, dimension( * ) dl, double precision, dimension( * ) d, double precision, dimension( * ) du, double precision, dimension( * ) du2, integer, dimension( * ) ipiv, double precision, dimension( ldb, * ) b, integer ldb)

DGTTS2 solves a system of linear equations with a tridiagonal matrix using the LU factorization computed by sgttrf. No cap, that's the whole flex. 💅

Purpose

Okay so here's the point, bestie: DGTTS2 solves one of the systems of equations

A*X = B  or  A**T*X = B,

with a tridiagonal matrix A using the LU factorization computed by DGTTRF. Iconic. 🌈

Parameters

• ITRANS — ITRANS is INTEGER. Specifies the form of the system of equations.
  • = 0: A * X = B (No transpose)
  • = 1: A**T* X = B (Transpose)
  • = 2: A**T* X = B (Conjugate transpose = Transpose)
• N — N is INTEGER. The order of the matrix A.
• NRHS — NRHS is INTEGER. The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0.
• DL — DL is DOUBLE PRECISION array, dimension (N-1). The (n-1) multipliers that define the matrix L from the LU factorization of A.
• D — D is DOUBLE PRECISION array, dimension (N). The n diagonal elements of the upper triangular matrix U from the LU factorization of A.
• DU — DU is DOUBLE PRECISION array, dimension (N-1). The (n-1) elements of the first super-diagonal of U.
• DU2 — DU2 is DOUBLE PRECISION array, dimension (N-2). The (n-2) elements of the second super-diagonal of U.
• IPIV — IPIV is INTEGER array, dimension (N). The pivot indices; for 1 <= i <= n, row i of the matrix was interchanged with row IPIV(i). IPIV(i) will always be either i or i+1; IPIV(i) = i indicates a row interchange was not required.
• B — B is DOUBLE PRECISION array, dimension (LDB,NRHS). On entry, the matrix of right hand side vectors B. On exit, B is overwritten by the solution vectors X.
• LDB — LDB is INTEGER. The leading dimension of the array B. LDB >= max(1,N).

Author

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

Definition at line 127 of file dgtts2.f.

📝 Author 📝

Generated automatically by Doxygen for LAPACK from the source code.

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That's the whole page, bestie — footer facts: LAPACK Version 3.12.0, source SRC/dgtts2.f(3), and the footer doesn't print a separate date, so that's the whole cute sign-off. Stay slay and solve those tridiagonal systems. 💖✨👑