NAME

dstsv - compute the solution to a system of linear equations A ∗ X = B where A is a symmetric tridiagonal matrix

SYNOPSIS

SUBROUTINE DSTSV( N, L, D, SUBL, IPIV, INFO )

INTEGER INFO, N

DOUBLE PRECISION D( ∗ )

DOUBLE PRECISION L( ∗ ), SUBL( ∗ )

#include <sunperf.h>

void dstsv(int n, double ∗l, double ∗d, double ∗subl, int ∗info) ;

PURPOSE

DSTSV computes the solution to a system of linear equations A ∗ X = B where A is a symmetric tridiagonal matrix. 
 

ARGUMENTS

N (input) INTEGER
The order of the matrix A.  N >= 0.

L (input/output) DOUBLE PRECISION array, dimension (N)
On entry, the n-1 subdiagonal elements of the tridiagonal matrix A.  On exit, part of the factorization of A.

D (input/output) DOUBLE PRECISION array, dimension (N)
On entry, the n diagonal elements of the tridiagonal matrix A.  On exit, the n diagonal elements of the diagonal matrix D from the factorization of A.

SUBL (output) DOUBLE PRECISION array, dimension (N)
On exit, part of the factorization of A.

IPIV (output) INTEGER array, dimension (N)
On exit, the pivot indices of the factorization.

INFO (output) INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, D(k,k) is exactly zero.  The factorization has been completed, but the block diagonal matrix D is exactly singular and division by zero will occur if it is used to solve a system of equations.

SunOS 5.0  —  Last change: 10 Dec 1998