NAME

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

SYNOPSIS

  SUBROUTINE SSTSV( N, NRHS, L, D, SUBL, B, LDB, IPIV, INFO)
  INTEGER N, NRHS, LDB, INFO
  INTEGER IPIV(*)
  REAL L(*), D(*), SUBL(*), B(LDB,*)

  SUBROUTINE SSTSV_64( N, NRHS, L, D, SUBL, B, LDB, IPIV, INFO)
  INTEGER*8 N, NRHS, LDB, INFO
  INTEGER*8 IPIV(*)
  REAL L(*), D(*), SUBL(*), B(LDB,*)

F95 INTERFACE

  SUBROUTINE STSV( [N], [NRHS], L, D, SUBL, B, [LDB], IPIV, [INFO])
  INTEGER :: N, NRHS, LDB, INFO
  INTEGER, DIMENSION(:) :: IPIV
  REAL, DIMENSION(:) :: L, D, SUBL
  REAL, DIMENSION(:,:) :: B

  SUBROUTINE STSV_64( [N], [NRHS], L, D, SUBL, B, [LDB], IPIV, [INFO])
  INTEGER(8) :: N, NRHS, LDB, INFO
  INTEGER(8), DIMENSION(:) :: IPIV
  REAL, DIMENSION(:) :: L, D, SUBL
  REAL, DIMENSION(:,:) :: B

C INTERFACE

#include <sunperf.h>

void sstsv(int n, int nrhs, float *l, float *d, float *subl, float *b, int ldb, int *ipiv, int *info);

void sstsv_64(long n, long nrhs, float *l, float *d, float *subl, float *b, long ldb, long *ipiv, long *info);

PURPOSE

sstsv 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.
NRHS (input)
The number of right hand sides in B.
L (input/output)
```
 REAL 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)
```
 REAL 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)
```
 REAL array, dimension (N)
```
On exit, part of the factorization of A.
B (input/output)
The columns of B contain the right hand sides.
LDB (input)
The leading dimension of B as specified in a type or DIMENSION statement.
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.