function output ( f, ibc, indx, n, nu, ul, ur, xn )

%% OUTPUT prints out the computed solution.
%
%  Modified:
%
%    06 November 2006
%
%  Parameters:
%
%    Input, real F(NU).
%    ASSEMBLE stores into F the right hand side of the linear
%    equations.
%    SOLVE replaces those values of F by the solution of the
%    linear equations.
%
%    Input, integer IBC.
%    IBC declares what the boundary conditions are.
%    1, at the left endpoint, U has the value UL,
%       at the right endpoint, U' has the value UR.
%    2, at the left endpoint, U' has the value UL,
%       at the right endpoint, U has the value UR.
%    3, at the left endpoint, U has the value UL,
%       and at the right endpoint, U has the value UR.
%    4, at the left endpoint, U' has the value UL,
%       at the right endpoint U' has the value UR.
%
%    Input, integer INDX(0:N).
%    For a node I, INDX(I) is the index of the unknown
%    associated with node I.
%    If INDX(I) is equal to -1, then no unknown is associated
%    with the node, because a boundary condition fixing the
%    value of U has been applied at the node instead.
%    Unknowns are numbered beginning with 1.
%    If IBC is 2 or 4, then there is an unknown value of U
%    at node 0, which will be unknown number 1.  Otherwise,
%    unknown number 1 will be associated with node 1.
%    If IBC is 1 or 4, then there is an unknown value of U
%    at node N, which will be unknown N or N+1,
%    depending on whether there was an unknown at node 0.
%
%    Input, integer N
%    The number of subintervals into which the interval
%    [XL,XR] is broken.
%
%    Input, integer NU.
%    NU is the number of unknowns in the linear system.
%    Depending on the value of IBC, there will be N-1,
%    N, or N+1 unknown values, which are the coefficients
%    of basis functions.
%
%    Input, real UL.
%    If IBC is 1 or 3, UL is the value that U is required
%    to have at X = XL.
%    If IBC is 2 or 4, UL is the value that U' is required
%    to have at X = XL.
%
%    Input, real UR.
%    If IBC is 2 or 3, UR is the value that U is required
%    to have at X = XR.
%    If IBC is 1 or 4, UR is the value that U' is required
%    to have at X = XR.
%
%    Input, real XN(0:N).
%    XN(I) is the location of the I-th node.  XN(0) is XL,
%    and XN(N) is XR.
%
  fprintf ( 1, '\n' );
  fprintf ( 1, 'Node    X(I)        U(X(I))        Uexact        Error\n' );
  fprintf ( 1, '\n' );

  for i = 0 : n

    if ( i == 0 )

      if ( ibc == 1 | ibc == 3 )
        u = ul;
      else
        u = f(indx(i+1));
      end

    elseif ( i == n )

      if ( ibc == 2 | ibc == 3 )
        u = ur;
      else
        u = f(indx(i+1));
      end

    else

      u = f(indx(i+1));

    end

    uex = uexact ( xn(i+1) );
    error = u - uex;

    fprintf ( 1, '  %4d  %12f  %12f  %12f  %12f\n', i, xn(i+1), u, uex, error );

  end