function []=jacob(func,z)
// Copyright (C) 2001 Michel Juillard
// 
 
global('d1_','jacobia_','gstep_');
 
z = matrix(z,max(size(z)),1);
d1_ = evstr(func+'(z)');
nz = size(z,1);
jacobia_ = zeros(size(d1_,1),nz);
dh = max(abs(z),gstep_*ones(nz,1))*(%eps^(1/3));
xdh = z;
for j = 1:nz
  xdh(j) = xdh(j)+dh(j);
  h = xdh(j)-z(j);
  jacobia_(:,j) = (evstr(func+'(xdh)')-d1_)/h;
  xdh(j) = z(j);
end
 
// 8/27/2000 modified with function name MJ