Here is a link to what I am trying to do... I'm not sure what I am doing wrong.

http://ezekiel.vancouver.wsu.edu/~cs...ts/pdf/pdf.pdf

Here is my source code thus far...

Code:
#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#define INV_SQRT_2PI 0.39894228   /* 1/sqrt(2*pi) */
#define epsilon 0.0000001
double a, b, approx, u, U, O;
int x;
double o=epsilon;



double f(int x)
{	
	double f(int x); = exp(((double)x*x)/2);
	return f(x);
}
double S(double a, double b)
{
	double S(double a, double b); = ((b-a)/6)*(f(a)+4*f((a+b)/2)+f(b));
	return S(a,b);
}
double asimpson(double a,double b,double approx, double o)
{
	double c=(a+b)/2;
	double left=S(a,c);
	double right=S(c,b);
	double d=(left+right-approx)/15;
	if(abs(d)<=epsilon)
		return left+right+d;
	return asimpson(a,c,left,o/2)+asimpson(c,b,right,o/2);
}
int main(void)
{	
	scanf("%lf", &x);
	scanf("%lf", &U);
	scanf("%lf", &O);
	double p, u, o;
	u=(x-U)/O;
	p=(1/2)+INV_SQRT_2PI * asimpson(0,u,S(0,u),o);

	printf("pdf= %f",p);

return 0;
}
Values of x=72, U=69, and O=2.8 should give a p=0.85801

You'll all probably find it disgustingly crude, but I've never done any programming before... please be kind and help a newbie.