public class Calculator
{
    // instance variables - replace the example below with your own
    private double displayValue;
    private double memoryValue;
<<<<<<< HEAD

    //private CoreFeatures core;
    //private ScientificFeatures science;
    //private BonusFeatures bonus;
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    private boolean err;
>>>>>>> 85cb6e118e199051f7fc22d59044b58cdf7dcf01

    /**
     * Constructor for objects of class Calculator
     */
    public Calculator()
    {
        displayValue = 0;
        memoryValue = 0;
        err = false;
    }

    //Memory set
    public double memSet(){
        memoryValue = displayValue;
        return memoryValue;
    }

    public double memClear(){
        memoryValue = 0;
        return memoryValue;
    }

    public double mrc(){
        displayValue = memoryValue;
        return displayValue;
    }

    //Clear and retrieve display value
    public double clear(){
        displayValue = 0;
        err = false;
        return displayValue;
    }

    public double getDisplayValue(){
        return displayValue;
    }

    //basic functions
    public double add(double value1, double value2){
        displayValue = value1 + value2;
        return displayValue;
    }

    public double subtract(double value1, double value2){
        displayValue  = value1 - value2;
        return displayValue;
    }

    public double multiply(double value1, double value2){
        displayValue = value1 * value2;
        return displayValue;
    }

    public double divide(double dividend, double divisor){
        displayValue = dividend / divisor;
        return displayValue;
    }

    public double pow(double base, double exponent){
        displayValue = Math.pow(base, exponent);
        return displayValue;
    }

    public double square(double base){
        return pow(base, 2);
    }

    public double squareRoot(double value){
        displayValue = Math.sqrt(value);
        return displayValue;
    }

    public double inverse(double value){
        displayValue = 1 / value;
        return displayValue;
    }

    public double changeSign(double value){
        return multiply(value, -1);
    }

    //scientific functions
    public double sin(double value){
        displayValue = Math.sin(value);
        return displayValue;
    }

    public double cos(double value) {
        displayValue = Math.cos(value);
        return displayValue;
    }

    public double tan(double value) {
        displayValue = Math.tan(value);
        return displayValue;
    }

    public double log(double value) {
        displayValue = Math.log(value);
        return displayValue;
    }

    public double inverseSin(double value) {
        displayValue = Math.log(value);
        return displayValue;
    }

    public double inverseCos(double value) {
        displayValue = Math.acos(value);
        return displayValue;
    }

    public double inverseTan(double value) {
        displayValue = Math.atan(value);
        return displayValue;
    }

    public double inverseLog(double value){
        displayValue = Math.pow(value, 10);
        return displayValue;
    }

    public double naturalLog(double value) {
        displayValue = Math.log1p(value);
        return displayValue;
    }

    public double inverseLn(double value) {
        displayValue = Math.pow(Math.E, value);
        return displayValue;
    }

    public double displayPi() {
        displayValue = Math.PI;
        return displayValue;
    }

    public double displayE(){
    displayValue = Math.E;
    return Math.E;
    }

}