function [jacob2_]=jacob2(func,x,varargin)
jacob2_=[];
// Copyright (C) 2001 Michel Juillard
// 
// computes second order partial derivatives
// uses Abramowitz and Stegun (1965) formulas 25.3.24 and 25.3.27 p. 884
 
n = size(x,1);
nargin = length(varargin);

//h1=max(abs(x),gstep_*ones(n,1))*eps^(1/3);
h1 = max(abs(x),sqrt(gstep_)*ones(n,1))*(%eps^(1/6));
h_1 = h1;
xh1 = x+h1;
h1 = xh1-x;
xh1 = x-h_1;
h_1 = x-xh1;
xh1 = x;
 
if nargin > 2 then
  f0 = evstr(func+'(x,varargin)');
  else
  f0 = evstr(func+'(x)');
end
f1 = zeros(size(f0,1),n);
f_1 = f1;
 
for i = 1:n
  xh1(i) = x(i)+h1(i)
  if nargin > 2
    f1(:,i) = evstr(func+'(xh1,varargin)');
  else
    f1(:,i) = evstr(func+'(xh1)');
  end
  xh1(i) = x(i)-h_1(i);
  if nargin > 2
    f_1(:,i) = evstr(func+'(xh1,varargin)');
  else
    f_1(:,i) = evstr(func+'(xh1)');
  end
  xh1(i) = x(i);
  i = i+1;
end
xh_1 = xh1;

jacob2_ = sparse([],[],[size(f0,1) n*n]);
for i = 1:n
  if i>1 then
    k = i:n:n*(i-1);
    jacob2_(:,(i-1)*n+1:(i-1)*n+i-1) = jacob2_(:,k);
  end
  jacob2_(:,(i-1)*n+i) = sparse((f1(:,i)+f_1(:,i)-2*f0) ./ (h1(i)*h_1(i)));
  temp = f1+f_1-f0*ones(1,n);
  for j = i+1:n
    xh1(i) = x(i)+h1(i);
    xh1(j) = x(j)+h_1(j);
    xh_1(i) = x(i)-h1(i);
    xh_1(j) = x(j)-h_1(j);
    if nargin > 2 then
      jacob2_(:,(i-1)*n+j) = sparse(-(-evstr(func+'(xh1,varargin)')-evstr(func+'(xh_1,varargin)')+temp(:,i)+temp(:,j)) ./ (2*h1(i)*h_1(j)));
    else
      jacob2_(:,(i-1)*n+j) = sparse(-(-evstr(func+'(xh1)')-evstr(func+'(xh_1)')+temp(:,i)+temp(:,j)) ./ (2*h1(i)*h_1(j)));
    end
    xh1(i) = x(i);
    xh1(j) = x(j);
    xh_1(i) = x(i);
    xh_1(j) = x(j);
    j = j+1;
  end
  i = i+1;
end
 
// 10/21/02 MJ used the 7 points formula