help to do operation on polynomial

Hello,
I am trying to write functions to do addition/sub and multiplication of two poly.
I searched the web and tried several things which they didn't work out.
So what is the best way to implement addition on two polynomials?

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//Project 1

#include "stdafx.h"
#include <iostream>
#include <vector>
#include <string>
using namespace std;
//#include <ginac/ginac.h>
//using namespace GiNaC;


//Poly class definition
class poly{
public:
	poly();
	poly(unsigned int);
	poly(string, unsigned int);
	poly(string, unsigned int, double[]);
	poly(const poly&);
	poly(vector<double> &coeffs);
	//Two ways of setting polynomials
	void setPoly(double);
	void setPoly(double[]);
	double getcoeff(double n);
	//vector<double> getAllCoeff();
	void printPoly();
	double eval(double);
	//First, second derivative and first integral estimation 
	double Fderiv(double);
	double Sderiv(double);
	double Fintegral(double, double);
	double Rroot(double);
	poly add(poly &poly1, poly &poly2);
private:
	string name;
	int order;
	vector<double>coeff;
};
//*************** Poly class constructors definiation*************\\

//default constructors
poly::poly() {
	order = 0;
	coeff.push_back(0);
}
//overloaded constructor with given poly order
poly::poly(unsigned int n) {
	order = n;
}
//overloaded constructor with given poly name and order
poly::poly(string p, unsigned int n) {
	name = p;
	order = n;
}
//overloaded constructor with given poly name, order, and coefficients
poly::poly(string p, unsigned int n, double c[]) {
	name = p;
	order = n;
	for (unsigned int i = 0; i <= n; i++)
		coeff.push_back(c[i]);  //notice that the array c has n+1 elements
}
poly::poly(const poly& p) {		//copy constructor
	name = p.name;
	order = p.order;
	for (unsigned int i = 0; i <= order; i++)
		coeff.push_back(p.coeff[i]);
}
//set function used to set the coeff one at time
void poly::setPoly(double x) {	
	//coeff.push_back(x);
	if (order == 0)
		coeff.pop_back();
	coeff.push_back(x);
	order++;
}
//set function used to set all coeff using array
void poly::setPoly(double c[]) {	
	for (unsigned int i = 0; i <= order; i++)
		coeff.push_back(c[i]);
}
poly::poly(vector<double> &coeffs) {
	for (unsigned int i = 0; i <= order; i++)
		coeff.push_back(coeffs[i]);
}
//printPoly function to print polynomial in nreadable format
void poly::printPoly() {	
	/*unsigned int i = 0;
	cout << "Polynomial Name: " << name << endl;
	cout << "Order: " << n << endl;
	//for (unsigned int i = 0; i <= order; i++)
	for (; n >= 0; i++, n--)
	if (n == 0)
		cout << coeff[i] << endl;
	else if (n>=1)
		cout << "Coefficients are: ";
		cout << coeff[i] << "*x^"<<n<<"+";
		*/
	cout << "Polynomial Name: " << name << endl;
	cout << "Order: " << order << endl;
	cout << "Coefficients are: ";
	for (unsigned int i = 0; i <= order; i++)
		cout << coeff[i] << " ";
	cout << endl;
}
//polynomial evaluation using Horner's Factorization
double poly::eval(double x) {	
	double ans = 0.0;
	for (unsigned int i = 0; i <= order; i++)
		ans = ans * x + coeff[i];
	return ans;
}
//getfoeff function read a spicified coefficient value
double poly::getcoeff(double n) {
	return coeff[n];
}
//returns all coeff of poly 
/*
vector<double> poly::getAllCoeff() {	
	return coeff;
}*/
//integNT function for numerical integral estimate  using the trapezoidal rule or Simpson's 1/3 rule
double poly::Fintegral(double a, double b) {	
	int n = 200; // assume 200 panels
	double h = (b - a) / n;
	double t = eval(a) + eval(b);
	double sum = 0;
	for (int i = 1; i<n; i++)
		sum += eval(a + i*h);
	return (h / 2)*(t + 2 * sum);
}
double poly::Sderiv(double x) {
	double h = 1.0e-2;
	double d1, d2, d3; //ans;
	d1 = eval(x + h);
	d2 = 2*eval(x);
	d3 = eval(x - h);
	return (d1 - d2 +d3) / (h * h);
}
//First derivative numerical estimate
double poly::Fderiv(double x) {	
	double h = 1.0e-2;
	double d1, d2; //ans
	d1 = eval(x + h);
	d2 = eval(x - h);
	return (d1 - d2) / (2 * h);
}
double poly::Rroot(double x) {
	return 0;
}

poly poly::add(poly &poly1, poly &poly2) {
	vector<double> temp1;
	if (poly1.order > poly2.order)
	{
		for (int i = 0; i < poly2.order; i++)
		{
			temp1[i] = poly1.getcoeff(i) + poly2.getcoeff(i);
		}
		poly temp0(temp1);
		return temp0;
	}
	else if (poly1.order < poly2.order)
	{
		for (int i = 0; i < poly1.order; i++)
		{
			temp1[i] = poly1.getcoeff(i) + poly2.getcoeff(i);
		}
		poly temp0(temp1);
		return temp0;
	}
}
int _tmain(int argc, _TCHAR* argv[])
{

	double cq[]={1,2,5,1};
	poly q("poly", 3, cq);
	
	double cr[] = { 1,6,11,6 };
	poly r( "poly", 3, cr);
	cout <<"Coefficient at 1: "<< r.getcoeff(1) << endl;
	r.setPoly(1);
	r.printPoly();
	cout << "poly evaluated at 1: " << r.eval(1) << endl;
	cout << "poly evaluated at 5: "  << r.eval(5) << endl;
	cout << "poly evaluated at -2: " << r.eval(-2.0) << endl;
	cout << r.Fintegral(0, 3) << endl; // estimate the integral from 0 to 3 using Trap rule
	cout << "Estimate first derivative of polynomial at: "<< r.Fderiv(3) << endl;
	cout << "Estimate second derivative of polynomial at: " << r.Sderiv(3) << endl;
	d.add(r, q);

	return 0;
}
Last edited on
Just add the two polynomials coefficient by coefficient. What's the problem?
1
2
for (int i = 0; i <= max(a.degree(), b.degree()); i++)
    c.coefficient(i) = a.coefficient(i) + b.coefficient(i);
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