double f5 ( double h ) 
{
  double pi = 3.14159265;
  double r = 3.0; 
  double value;

  value = r * r * acos ( ( r - h ) / r ) 
    - ( r - h ) * sqrt ( h * ( 2 * r - h ) ) 
    - 0.25 * pi * r * r;

  return value;
}