# spttrs.f - Man Page

## Synopsis

### Functions/Subroutines

subroutine **spttrs** (**N**, **NRHS**, D, E, B, **LDB**, INFO)**SPTTRS**

## Function/Subroutine Documentation

### subroutine spttrs (integer N, integer NRHS, real, dimension( * ) D, real, dimension( * ) E, real, dimension( ldb, * ) B, integer LDB, integer INFO)

**SPTTRS**

**Purpose:**

SPTTRS solves a tridiagonal system of the form A * X = B using the L*D*L**T factorization of A computed by SPTTRF. 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.

**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 REAL array, dimension (N) The n diagonal elements of the diagonal matrix D from the L*D*L**T factorization of A.

*E*E is REAL 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 REAL 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.

**Date:**December 2016

Definition at line 111 of file spttrs.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page spttrs(3) is an alias of spttrs.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK