#include "Poly.h"
#include <cmath>

Poly::Poly(int order)       // Default constructor
{
    int i;
    order = order + 1;
    a = new double [order+1];
    for (i=0;i<order+1;i++) a[i] = 0.0;
}

Poly::Poly(const Poly &p)  // Copy constructor
{
    int i;
    order = p.order+1;
    a = new double [order+1];
    for (i=0;i<order+1;i++) a[i] = p.a[i];

}

Poly::~Poly()
{
delete [] a;
}

//Functions

void Poly::Resize(int newlength)
{  
    if (order+1 != newlength) {  
    if (order+1 > 0) delete [] a;
    a = new double [newlength];
    order = newlength;
  }  
}

Poly Poly:: operator=(const Poly &p)
{
  int i;
  Resize(p.order+1);
  for (i=0; i< order+1; i++) a[i] = p.a[i];  
  return(*this);  

}
Poly Poly::operator+(const Poly &p)
{
  int i;
  Poly temp(*this);
  for (i=0; i< order+1; i++) temp.a[i] += p.a[i];
  return temp;

}

Poly Poly::operator-(const Poly &p)
{
int i;
  Poly temp(*this);

  for (i=0; i< order+1; i--) temp.a[i] -= p.a[i];
  return temp;
}

Poly Poly::operator*(const Poly &p){

        int i, j;
        Poly temp;
        double b;
        for (i=0;i<order+1; i++) {
            b = a[i];
            for (j=0; j <p.order+1;j++) {
                temp = temp+ b*p.a[j];
            }
        }
        return temp;
}

double Poly::Evaluate(double a){  // Compute and return the polynomial value at x
    /*double temp, b;
    int i;
    for (i=0; i<order+1; i++) {
        b = a[i];
        temp +=  b * pow(a, i); // something wrong here!!!
    }
    return temp;*/
    return 0;
}

void Poly::SetCoeff(int o, double a){

    return;
}

istream &operator>>(istream &is, Poly &p)
{
    cout<<"Enter Polynomial order: \n";
    int order;
    is>>order;
    p.Resize(order+1);

    cout<<"Enter coefficients: \n";
    int i;
    for (i=0; i<p.order+1; i++) {
        double b;
        is>>b;
        p.a[i]=b;
    }
    return is;

}
ostream &operator<<(ostream &os, Poly &p)
{
    int i;
    for (i=p.order; i>1; i--) {
        os<<p.a[i]<<"*x^"<<i-1<<"+";
    }
    os<<p.a[1];
    return os;
}