question: private static void check ( double x , double y ) { double eps = Math . pow ( 2.0 , - 52.0 ) ; if ( x == 0 & Math . abs ( y ) < 10 * eps ) return ; if ( y == 0 & Math . abs ( x ) < 10 * eps ) return ; if ( Math . abs ( x - y ) > 10 * eps * Math . max ( Math . abs ( x ) , Math . abs ( y ) ) ) { throw new RuntimeException ( "The difference x-y is too large: x = " + Double . toString ( x ) + "  y = " + Double . toString ( y ) ) ; } }
target:  Check magnitude of difference of scalars.