ZCW-MacroLabs-OOP-ScientificCalculator/BonusFeatures.java

import java.math.BigInteger;

/**
 * Write a description of class BonusFeatures here.
 *
 * @author (your name)
 * @version (a version number or a date)
 */
public class BonusFeatures
{
    CoreFeatures coreFeatures = new CoreFeatures();
    
    public double factorial(double x) {
        
        if (x % 1 != 0){
            coreFeatures.error();
            return 0;
        }
        
        int y = (int)x;
        BigInteger factorial = new BigInteger("1");
        
        for(int i = y; i > 1; i--){
            factorial = factorial.multiply(BigInteger.valueOf(i));
        }
        
        return Double.parseDouble(factorial.toString());
    }

    public double log(double x) {
        return Math.log10(x);
    }

    public double inverseLog(double x) {
        return Math.pow(10,x);
    }

    public double naturalLog(double x) {
        return Math.log(x);
    }

    public double inverseNaturalLog(double x) {
        return Math.pow(Math.E,x);
    }
}