package question2;

/*represents a polynomial with a
 *  degree and coefficients
 *  can have a whole number degree
 *  and a array of coefficients sized based on degree
 */
public class Polynomial {

    int degree;
    double[] coefficients;

/*
 * regular constructor for polynomial
 * only fills the degree variable of object
 */
public Polynomial(int deg) {
    degree=deg;
    coefficients=new double[deg+1];
}

/*
 * copy constructor
 */
public Polynomial(Polynomial p) {
    this.degree=p.degree;
    this.coefficients = p.coefficients.clone();
}

/*
 * sets value of coefficient in array, use in loop the index
 * is the number of coefficients in polynomial equation
 * based on standard polynomial equation
 */
public void setCoefficient(int index, double value) {
    coefficients[index]=value;
}

/*
 * supply value of coefficient from array, use in loop
 */
public double getCoefficient(int index) {
    double value=this.coefficients[index];
    return value;
}

/*
 * Calculates y of fully constructed polynomial given a x
 */
public double evaluate(double x){
    double value=this.coefficients[0];
    for(int i=0; i<=this.degree; i++) {
        value=value+(  (this.coefficients[i])  *   (Math.pow(x, i))    );
    }
    return value;

}

/*
 * Determines if two polynomials are equal
 * compares degree and coefficients in order
 */
public boolean equals(Polynomial poly) {

    if(poly.degree==this.degree) {
        for(int i=0; i<this.degree; i++) {
            if(this.coefficients[i]!=poly.coefficients[i]) {
                return false;
            }
        }
        return true;
    }
    return false;
}


/*
 * converts polynomial to string
 * as visual of equation
 */
public String toString() {
    String out=""+this.coefficients[0];


    for(int i=1; i<=this.degree; i++) {
        if(this.coefficients[i]>0)
        out=out+" + ("+this.coefficients[i]+")x^"+i;
    }
    return out;
}

}