SPTTS2(3)      LAPACK routine of NEC Numeric Library Collection      SPTTS2(3)



NAME
       SPTTS2

SYNOPSIS
       SUBROUTINE SPTTS2 (N, NRHS, D, E, B, LDB)



PURPOSE
            SPTTS2 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.




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

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

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



LAPACK routine                  31 October 2017                      SPTTS2(3)