function []=nonunifgrid(itype)
% Numerical experiments with finite volume solution of
% convection-diffusion equation on uniform and non-uniform grids
% Needs: convection_diffusion.m,  exact_solution.m

% [norminf]=convection_diffusion(a,b,pe,m1,m2,refinement,pl)
% Input parameters
% a          Left Dirichlet value
% b          Right Dirichlet value
% pe         Peclet number
% m1         Number of cells outside refinement zone
% m2         Number of cells inside refinement zone
% refinement 1 local grid refinement (del = 8/Pe) 
%            0 uniform grid
% pl = 1     Plot results
%
% Output parameter
% norminf    maximum error


if itype==0
  % Solve different examples (show zooms)
  convection_diffusion(0, 1, 40, 16, 0, 0, 1) % Nonuniform, 16 cells
%  convection_diffusion(0, 1, 40, 8, 8, 1, 1)  % Uniform, 16 cells
%  convection_diffusion(0, 1, 40, 40, 0, 0, 1) % Same error as
%                                              % nonuniform (40 cells)
%  convection_diffusion(0, 1, 1000, 8, 8, 1, 1) % Same error, Pe = 1000
%  convection_diffusion(0, 1, 1000, 16, 0, 0, 1) % Pe = 1000, uniform
%  convection_diffusion(0, 1, 1000, 8, 32, 1, 1) % Low error, > points \ 
                                                %  in BL only
elseif itype==1
  % Vary Pe for a fixed number of grid points on nonuniform grid
  for j = 1:6
    pe(j) = 2^(j+4);
    norminf(j)=convection_diffusion(0,1,pe(j),8,8,1,0);
  end
  plot(pe,norminf,'o-');grid on; xlabel('Pe');ylabel('Error');
  axis([0 1200 0 0.2]);
elseif itype == 2
  % Vary number of grid points for fixed Pe on nonuniform grid
  pe = 1e2;
  for j = 1:8
    m1(j) = 8*2^j;
    m2(j) = 4*2^j;
    norminf(j)=convection_diffusion(0,1,pe,m1(j),m2(j),1,0);
  end
  loglog(m1+m2,norminf,'o');xlabel('J');ylabel('Error');hold on;
  loglog(m1+m2,2e1*(m1+m2).^(-2)*3.5);
  legend('Error','J^{-2}');
end