function y = roller ( x )

%  Integral from 0 to 4 is -2.9878

  y =     cos (       x ) ...
    + 5 * cos ( 1.6 * x ) ...
    - 2 * cos ( 2.0 * x ) ...
    + 5 * cos ( 4.5 * x ) ...
    + 7 * cos ( 9.0 * x );

  return
end
