sptsv(3F)

NAME
     SPTSV - compute the solution to a real system of linear equations A*X =
     B, where A is an N-by-N symmetric positive definite tridiagonal matrix,
     and X and B are N-by-NRHS matrices

SYNOPSIS
     SUBROUTINE SPTSV( N, NRHS, D, E, B, LDB, INFO )

         INTEGER       INFO, LDB, N, NRHS

         REAL          B( LDB, * ), D( * ), E( * )

PURPOSE
     SPTSV computes the solution to a real system of linear equations A*X = B,
     where A is an N-by-N symmetric positive definite tridiagonal matrix, and
     X and B are N-by-NRHS matrices.

     A is factored as A = L*D*L**T, and the factored form of A is then used to
     solve the system of equations.


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

     NRHS    (input) INTEGER
             The number of right hand sides, i.e., the number of columns of
             the matrix B.  NRHS >= 0.

     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 A = L*D*L**T.

     E       (input/output) REAL array, dimension (N-1)
             On entry, the (n-1) subdiagonal elements of the tridiagonal
             matrix A.  On exit, 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 U**T*D*U factorization of A.)

     B       (input/output) REAL array, dimension (LDB,N)
             On entry, the N-by-NRHS right hand side matrix B.  On exit, if
             INFO = 0, the N-by-NRHS solution matrix X.

     LDB     (input) INTEGER
             The leading dimension of the array B.  LDB >= max(1,N).

     INFO    (output) INTEGER
             = 0:  successful exit
             < 0:  if INFO = -i, the i-th argument had an illegal value
             > 0:  if INFO = i, the leading minor of order i is not positive
             definite, and the solution has not been computed.  The
             factorization has not been completed unless i = N.