Find the roots of equation(x3-4x-9)Newton Raphson method.

 #include<stdio.h>

#include<math.h>

double f(double x)

{

return x*x*x-4*x-9;

}

double fd(double x)

{

return 3*x*x-4;

}

void main()

{

int i=1;

double a,b,tol;

printf("Enter value of y0:");

scanf("%lf",&a);

printf("Enter tolerance:");

scanf("%lf",&tol);

while(1)

{

       b=a;

       a=a-f(a)/fd(a);

       printf(" y%d ---> %f\n",i++,a);

       if(fabs(a-b)<tol)

           break;

}

printf("\n Solution=%f",a);

}

Output:

Enter value of y0:2

Enter tolerance:0.00001

y1 ---> 3.125000

y2 ---> 2.768530

y3 ---> 2.708196

y4 ---> 2.706529

y5 ---> 2.706528

Solution=2.706528

Enter value of y0:3

Enter tolerance:0.00001

y1 ---> 2.739130

y2 ---> 2.706998

y3 ---> 2.706528

y4 ---> 2.706528

Solution=2.706528

Enter value of y0:5

Enter tolerance:0.00001

y1 ---> 3.647887

y2 ---> 2.953279

y3 ---> 2.730187

y4 ---> 2.706777

y5 ---> 2.706528

y6 ---> 2.706528

Solution=2.706528