function fjac = p01_jac ( n, x )

%*****************************************************************************80
%
%% p01_jac() sets the jacobian for problem 1.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%    10 October 2020
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    integer N, the number of variables and equations.
%
%    real X(N), the evaluation point.
%
%  Output:
%
%    real FJAC(N,N), the jacobian matrix.
%
  fjac = zeros ( n, n );

  fjac(1,1) = - 1.0;

  for i = 2 : n
    fjac(i,i-1) = - 20.0 * x(i-1);
    fjac(i,i) = 10.0;
  end

  return
end

