Secant.cpp

#include<iostream>
#include<cmath>//Secant Method
using namespace std;
struct function
{
	double fun1, fun2;
};
double calculate_fx(int* coeff, double a, int deg)//to find value in actual function
{
	double po, temp = deg, final = 0;
	for (int i = 0; i < deg + 1; i++)
	{
		po = pow(a, temp);
		po = coeff[i] * po;
		final += po;
		temp--;
	}
	return final;
}

void display(int* coeff_arr, int deg)//displaying equation
{
	cout << endl << "             <--------------------------------------Equation--------------------------------->" << endl << endl;
	cout << "                                          ";
	int temp = deg;
	for (int i = 0; i < deg + 1; i++)
	{
		cout << "(" << coeff_arr[i] << ")" << "x^" << temp;
		if (i < deg)
		{
			cout << "+";
		}
		temp--;
	}
}

function intervalChecker(double a, double b, int* coeff_arr, int deg)
{
	function f;
	double fun1, fun2;
	do {
		a = a + 0.1;
		b = b - 0.1;
		fun1 = calculate_fx(coeff_arr, a, deg);
		fun2 = calculate_fx(coeff_arr, b, deg);
	} while (fun1 < 0 && fun2 < 0 || fun1>0 && fun2>0);
	f.fun1 = a;
	f.fun2 = b;
	return f;
}

int main()
{
	int* coeff_arr;
	int deg;
	double a, b, fun1, fun2,iter;
	double x, temp1, temp2;
	function f;
	cout << "Enter Highest Degree of x:";
	cin >> deg;
	int temp = deg;
	coeff_arr = new int[deg + 1];
	for (int i = 0; i < deg + 1; i++)
	{
		cout << "Enter Coefficient of x^" << temp << ":";
		cin >> coeff_arr[i];
		temp--;
	}
	system("cls");
	display(coeff_arr, deg);
	cout << endl;
	do {
		cout << "Enter Interval value a:";
		cin >> a;
		cout << "Enter Interval value b:";
		cin >> b;
		fun1 = calculate_fx(coeff_arr, a, deg);
		fun2 = calculate_fx(coeff_arr, b, deg);
		cout << "Interval value: [" << a << "," << b << "]" << endl;
		cout << "f(a):" << fun1 << endl;
		cout << "f(b):" << fun2 << endl;
	} while (fun1 < 0 && fun2 < 0 || fun1>0 && fun2>0);
	f = intervalChecker(a, b, coeff_arr, deg);//picking x0 and x1
	for (int i = 0; i < 15; i++)
	{
		temp1 = calculate_fx(coeff_arr, f.fun2, deg);
		temp2 = calculate_fx(coeff_arr, f.fun1, deg);
		x = (f.fun1 * temp1) - (f.fun2 * temp2);
		temp1 = temp1 - temp2;
		x = x / temp1;
		cout << "x[" << i+2 << "]=" << x << endl;
		f.fun1 = f.fun2;
		f.fun2 = x;
	}
}