?gtts2

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 10/15/2026

Version

Public

?gtts2

Solves a system of linear equations with a tridiagonal matrix using the LU factorization computed by ?gttrf .

Syntax

call sgtts2(itrans, n, nrhs, dl, d, du, du2, ipiv, b, ldb)
call dgtts2(itrans, n, nrhs, dl, d, du, du2, ipiv, b, ldb)
call cgtts2(itrans, n, nrhs, dl, d, du, du2, ipiv, b, ldb)
call zgtts2(itrans, n, nrhs, dl, d, du, du2, ipiv, b, ldb)

Include Files

mkl.fi

Description

The routine solves for X one of the following systems of linear equations with multiple right hand sides:

A*X = B, A^{T}*X = B, or A^{H}*X = B (for complex matrices only), with a tridiagonal matrix A using the LU factorization computed by ?gttrf (Computes the LU factorization of a tridiagonal matrix.) .

Input Parameters

itrans: INTEGER . Must be 0, 1, or 2. Indicates the form of the equations to be solved: If itrans = 0 , then A*X = B (no transpose). If itrans = 1 , then A^{T}*X = B (transpose). If itrans = 2 , then A^{H}*X = B (conjugate transpose).

n: INTEGER. Specifies the order of the matrix A. The value of n must be at least zero.

nrhs: INTEGER . The number of right-hand sides, i.e., the number of columns in B ( nrhs≥ 0 ).
dl , d , du , du2 , b: REAL for sgtts2 DOUBLE PRECISION for dgtts2 COMPLEX for cgtts2 DOUBLE COMPLEX for zgtts2 . Arrays: dl(n - 1) , d(n ) , du(n - 1) , du2(n - 2) , b(ldb,nrhs) . The array dl contains the ( n - 1) multipliers that define the matrix L from the LU factorization of A . The array d contains the n diagonal elements of the upper triangular matrix U from the LU factorization of A . The array du contains the ( n - 1) elements of the first super-diagonal of U . The array du2 contains the ( n - 2) elements of the second super-diagonal of U . The array b contains the matrix B whose columns are the right-hand sides for the systems of equations.
ldb: INTEGER . The leading dimension of b ; must be ldb≥ max(1, n) .
ipiv: INTEGER . Array, DIMENSION ( n ). The pivot indices array, as returned by ?gttrf .

Output Parameters

b: Overwritten by the solution matrix X .

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?gtts2

Syntax

Include Files

Description

Input Parameters

Output Parameters