The problem is as follows:
Your task is to find the four solutions to the equation sin(x) = exp(0.4x) in the region from zero to ten radians.
This is accomplished with iteration and interpolation.
The output from my program is shown below:
The 4 solutions to sin(x) = exp(0.4x) starting from x = 0 are:
Solution No. 1:
x (iteration only) = 0.809 with an error of 5.77136e005
x (with interpolation) = 0.808941 with an error of 2.32525e008
Solution No. 2:
x (iteration only) = 2.811 with an error of 0.00024367
x (with interpolation) = 2.8107 with an error of 3.94877e008
Solution No. 3:
x (iteration only) = 6.362 with an error of 0.000244374
x (with interpolation) = 6.36176 with an error of 8.23243e009
Solution No. 4:
x (iteration only) = 9.402 with an error of 0.00048913
x (with interpolation) = 9.40151 with an error of 3.37411e009
So far I have written coding to find the solution for the first iteration. I'm not sure how to use the range, (or how to show this in radians); also, my solution is not correct. Can anybody tell me what my problem is?
Lastly, should I use a for loop to show the 4 solutions, or is there something else I should be doing?
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

//Iteration and Interpolation
//David Karayof
//October 25, 2013
#include <cmath>
#include <iostream>
using namespace std;
double Fx(double x);
double interp(double x, double step);
int main ()
{
double x= 0, step = 0.001 ;
while (Fx(x) > 0.0)
x = x + step;
cout << "\n x (iteration only) = " << x;
cout << "\n with an error of " << Fx(x);
x = interp(x,step);
cout << "\n\n x (with interpolation) = " << x;
cout << "\n with an error of " << Fx(x);
cout << "\n\n";
return 0;
}
double Fx(double x)
{
return((sin(x))  (exp(0.4 * x)));
}
double interp(double x, double step)
{
double ratio;
ratio =  Fx(xstep)/Fx(x);
return (x  step + ratio * step /(1 + ratio));
}
 