question: public static void UF8 ( 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 ; 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 ++ ; } } f [ 0 ] = Math . cos ( 0.5 * PI * x [ 0 ] ) * Math . cos ( 0.5 * PI * x [ 1 ] ) + 2.0 * sum1 / ( double ) count1 ; f [ 1 ] = Math . cos ( 0.5 * PI * x [ 0 ] ) * Math . sin ( 0.5 * PI * x [ 1 ] ) + 2.0 * sum2 / ( double ) count2 ; f [ 2 ] = Math . sin ( 0.5 * PI * x [ 0 ] ) + 2.0 * sum3 / ( double ) count3 ; }
target:  Evaluates the UF8 problem.