question: public static void UF9 ( double [ ] x , double [ ] f , int nx ) { int count1 = 0 ; int count2 = 0 ; int count3 = 0 ; double sum1 = 0.0 ; double sum2 = 0.0 ; double sum3 = 0.0 ; double yj ; double E = 0.1 ; for ( int j = 3 ; j <= nx ; j ++ ) { yj = x [ j - 1 ] - 2.0 * x [ 1 ] * Math . sin ( 2.0 * PI * x [ 0 ] + j * PI / nx ) ; if ( j % 3 == 1 ) { sum1 += yj * yj ; count1 ++ ; } else if ( j % 3 == 2 ) { sum2 += yj * yj ; count2 ++ ; } else { sum3 += yj * yj ; count3 ++ ; } } yj = ( 1.0 + E ) * ( 1.0 - 4.0 * ( 2.0 * x [ 0 ] - 1.0 ) * ( 2.0 * x [ 0 ] - 1.0 ) ) ; if ( yj < 0.0 ) { yj = 0.0 ; } f [ 0 ] = 0.5 * ( yj + 2 * x [ 0 ] ) * x [ 1 ] + 2.0 * sum1 / ( double ) count1 ; f [ 1 ] = 0.5 * ( yj - 2 * x [ 0 ] + 2.0 ) * x [ 1 ] + 2.0 * sum2 / ( double ) count2 ; f [ 2 ] = 1.0 - x [ 1 ] + 2.0 * sum3 / ( double ) count3 ; }
target:  Evaluates the UF9 problem.