function J = p05_j ( m, n, x )

%*****************************************************************************80
%
%% p05_j() evaluates the jacobian for problem 5.
%
%  Licensing:
%
%    This code is distributed under the MIT license.
%
%  Modified:
%
%  Modified:
%
%    03 March 2026
%
%  Author:
%
%    John Burkardt
%
%  Input:
%
%    integer M, the number of equations.
%
%    integer N, the number of variables.
%
%    real X(N), the evaluation point.
%
%  Output:
%
%    real J(M,N), the jacobian matrix.
%
  J = zeros ( m, n );

  J(1,1) = 50.0 * x(2) / ( pi * ( x(1)^2 + x(2)^2 ) );
  J(1,2) = -50.0 * x(1) / ( pi * ( x(1)^2 + x(2)^2 ) );
  J(1,3) = 10.0;

  J(2,1) = 10.0 * x(1) / sqrt ( x(1)^2 + x(2)^2 );
  J(2,2) = 10.0 * x(2) / sqrt ( x(1)^2 + x(2)^2 );
  J(2,3) = 0.0;

  J(3,1) = 0.0;
  J(3,2) = 0.0;
  J(3,3) = 1.0;

  return
end
