?gtts2

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

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

sgtts2 dgtts2 cgtts2 zgtts2

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 . The order of the matrix A ( n≥ 0 ).
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