?dttrsb

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

Download PDF

ID 766686

Date 10/15/2026

Version

Public

?dttrsb

Solves a system of linear equations with a diagonally dominant tridiagonal coefficient matrix using the LU factorization computed by ?dttrfb .

Syntax

call sdttrsb(trans, n, nrhs, dl, d, du, b, ldb, info)
call ddttrsb(trans, n, nrhs, dl, d, du, b, ldb, info)
call cdttrsb(trans, n, nrhs, dl, d, du, b, ldb, info)
call zdttrsb(trans, n, nrhs, dl, d, du, b, ldb, info)

call dttrsb(dl, d, du, b [, trans] [, info])

Include Files

mkl.fi , mkl_lapack.f90

Description

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

\(A * X = B\)

if trans = ‘N’ ,

\(A^T * X = B\)

if trans = ‘T’ ,

\(A^H * X = B\)

if trans = ‘C’ (for complex matrices only).

Before calling this routine, call ?dttrfb (Computes the factorization of a diagonally dominant tridiagonal matrix.) to compute the factorization of A .

Input Parameters

trans

CHARACTER*1 . Must be ‘N’ or ‘T’ or ‘C’ .

Indicates the form of the equations solved for \(X\) :

If trans = 'N' , then \(A * X = B\) .

If trans = 'T' , then \(A^T * X = B\) .

If trans = 'C' , then \(A^H * X = B\) .

n

INTEGER . The order of A ; n ≥ 0.

nrhs

INTEGER . The number of right-hand sides, that is, the number of columns in B ; nrhs ≥ 0.

dl , d , du , b

REAL for sdttrsb

DOUBLE PRECISION for ddttrsb

COMPLEX for cdttrsb

DOUBLE COMPLEX for zdttrsb .

Arrays: dl(n -1) , d(n) , du(n -1) , b(ldb,nrhs) .

The array dl contains the (n - 1) multipliers that define the matrices \(L_1\) , \(L_2\) from the factorization of \(A\) .

The array d contains the n diagonal elements of the upper triangular matrix \(U\) from the factorization of \(A\) .

The array du contains the ( n - 1) elements of the superdiagonal of \(U\) .

The array b contains the matrix \(B\) whose columns are the right-hand sides for the systems of equations.

b

Array of size max(1, ldb * nrhs ). Contains the matrix \(B\) whose columns are the right-hand sides for the systems of equations.

ldb

INTEGER . The leading dimension of b ; ldb≥ max(1, n) .

Output Parameters

b

Overwritten by the solution matrix X .

info

INTEGER .

If info = 0 , the execution is successful.
If info = -i , the i -th parameter had an illegal value.

Select Your Language

Using Intel.com Search

Quick Links

Recent Searches

Advanced Search

Only search in

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

?dttrsb

Syntax

Include Files

Description

Input Parameters

Output Parameters