TheAlgorithms-C-Plus-Plus/Computer Oriented Statistical Methods/Secant_method.CPP

#include<iostream.h>
#include<conio.h>
#include<math.h>

float eq(float i)
{
	return (pow(i,3)-(4*i)-9);                 // original equation
}

void main()
{
	float a,b,z,c,m,n;
	clrscr();
	for(int i=0;i<100;i++)
	{
		z=eq(i);
		if(z>=0)
		{
			b=i;
			a=--i;
			goto START;
		}
	}

	START:

	cout<<"\nFirst initial: "<<a;
	cout<<"\nSecond initial: "<<b;
	for(i=0;i<100;i++)
	{
		float h,d;
		m=eq(a);
		n=eq(b);

		c=((a*n)-(b*m))/(n-m);
		a=b;
		b=c;

		z=eq(c);
		if(z > 0 && z<0.09)			// stoping criteria
		{
			goto END;
		}
	}

	END:
	cout<<"\n\nRoot: "<<c;
	getch();
}