function [ pl, ql, pr, qr ] = tumor_bc ( xl, ul, xr, ur, t )

%*****************************************************************************80
%
%% tumor_bc() sets the left and right boundary conditions.
%
%  Discussion:
%
%    The boundary conditions have the form
%
%      p(x,t,u) + q(x,t) * f(x,t,u,dudx) = 0
%
%  Input:
%
%    real XL, UL, the left spatial coordinate and solution value.
%
%    real XR, UR, the right spatial coordinate and solution value.
%
%    real T, the time coordinate.
%
%  Output:
%
%    real PL, QL, the coefficients for the left boundary condition.
%
%    real PR, QR, the coefficients for the right boundary condition.
%

%
%  On the left, U(1) = 1, and U(2) has zero flux.
%
  pl = [ ul(1)-1.0; 0.0 ];
  ql = [ 0.0; 1.0 ];
%
%  On the right, U(1) = 0, and U(2) = 1.
%
  pr = [ ur(1); ur(2)-1.0 ];
  qr = [ 0.0; 0.0 ];

  return
end

