
 
 Purpose
 =======
 
    LA_PTSV computes the solution to a linear system of equations 
 A*X = B, where A has tridiagonal form and is real symmetric or complex
 Hermitian and, in either case, positive definite, and where X and B are
 rectangular matrices or vectors. A is factored as A = L*D*L^H, where L 
 is a unit lower bidiagonal matrix and D is a diagonal matrix. The 
 factored form of A is then used to solve the above system.
 
 =========
 
        SUBROUTINE LA_PTSV( D, E, B, INFO=info )
            REAL(<wp>), INTENT(INOUT) :: D(:)
            <type>(<wp>), INTENT(INOUT) :: E(:), <rhs>
            INTEGER, INTENT(OUT), OPTIONAL :: INFO
        where
            <type> ::= REAL | COMPLEX
            <wp>   ::= KIND(1.0) | KIND(1.0D0)
            <rhs>  ::= B(:,:) | B(:)
 
 Arguments
 =========
 
 D      (input/output) REAL array, shape (:) with size(D) = n, where n 
        is the order of A.
        On entry, the diagonal of A.
        On exit, the diagonal of D.
 E      (input/output) REAL or COMPLEX array, shape (:), with 
        size(E) = n-1.
        On entry, the subdiagonal of A.
        On exit, the subdiagonal of L.
 B      (input/output) REAL or COMPLEX array, shape (:,:) with 
        size(B,1) = n or shape (:) with size(B) = n.
        On entry, the matrix B.
        On exit, the solution matrix X.
 INFO   Optional (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 of A is not 
             positive definite, and the solution has not been computed.
 	    The factorization has not been completed unless i = n.
        If INFO is not present and an error occurs, then the program is
        terminated with an error message.

