Fixed Point Iteration

 1/*
 2 By David Isaacson, 2003
 3 Released into the Public Domain
 4
 5 fixedpt.c
 6
 7 The puropse of this program is to find the zero near x=1 of
 8 f(x)=2x^3+4x^2-2x-5=0
 9
10this can be rearranged into x=g(x)=(-1/13)(2x^3+4x^2-15x-5)
11 */
12
13#include <stdio.h>
14#include <math.h>
15
16int main()
17{
18    float x;				//the start coord
19    float xnew;			//the end coord
20
21    printf("Hello\n");
22
23    printf("What value shall we start at? ");
24    scanf("%f",&xnew);
25
26    do
27    {
28	x=xnew;
29	xnew=(2*x*x*x+4*x*x-15*x-5)/-13;//x=g(x)
30    }while(x!=xnew);			//again going to the max of the software
31
32    printf("The graphs intersect at %.3f \n",xnew);
33    //this prints xnew to a precision of 3 decimal places
34
35    return 0;
36}
37
38/*
39 When I ran this on my computer, I recieved the result:
40
41 Hello
42 What value shall we start at? 1
43 The graphs intersect at 1.078
44 
45 */