function bkfmesh = bkfmesh(Theta,j,a,b,head)

%
%  bkfmesh = bkfmesh(Theta[,j[,a,b[,head]]])
%
%  does a mesh plot of $D^jG_\Theta(x,t)$ over [a,b]x[a,b] with n gridlines
%
%  there are defaults of j=0 
%  and a=min(Theta), b=max(Theta) if these are not given
%
%  the string head, if present, specifies the title for the graph
%
%  S. Waldron May 1994
%

% set defaults
if (nargin<2), j=0; end
if (nargin<3), a=min(Theta); b=max(Theta); end
if (nargin<5), head=' '; end

n=50;  % n = number of points plotted on each axis
h=(b-a)/n; x=[a:h:b]; t=[a:h:b];
for i=1:n+1
   spline=bkfspmak(x(i),j,Theta);
   z(:,i)=fnval(spline,t)';
end

mesh(x,t,z)  % do the mesh plot
xlabel('x')   % add x label
ylabel('t')   % add y label
title(head)   % add title

%  The mesh plot maybe saved by using the command
%print -depsc2 bkfmesh  (postscript 2 color)