I am new to c++ and trying to calculate `Xk+1 = Xk - a*Xk*h` for user entered values. Here's what I tried:

```
#include<stdio.h>

float fn_calculate(int x1, int x0, int a, float h)
{
    int x;
    int a;
    float h;
    int k;
    for(k=-1; k<=100; k++);
    {
     float x1=x0-a*x0*h;

     printf("please enter a 'x' value:\n");
     scanf("%f",&x);
     printf("please enter a 'a' value:\n");
     scanf("%f",&a);
     printf("please enter a 'h' value:\n");
     scanf("%f",&h);
     printf("the result is: %f\n", x1);
    }
    return 0;
}

```