function T = temperature ( X, Y )
%
%% TEMPERATURE defines a temperature field T(X,Y).
%
% X, Y, and T are arrays so use dot operators!
%
  arg1 = -0.4  * (      (X-1.0) .^ 2 + 0.7 * (Y-3.0) .^ 2 );
  arg2 = -0.2 * ( 2.0 * (X-5.0) .^ 2 + 1.5 * (Y-1.0) .^ 2 );
  T = 100.0 * exp ( arg1 ) + 80.0 * exp ( arg2 );

  return
end