lab 3 part D

#include <stdio.h>//standard input out put library.
#include <math.h>// standard libraries for the math functions
#include <stdlib.h>
#define Pi 3.14159265

double divide(double X, double Y){// prototypes and the definitions
  return X/Y;
}
double multiply(double num1, double num2){
  return num1*num2;
}
double exp(double d);
double sub(double num1, double num2){
  return num1-num2;
}
double sqrt(double X);
double pow(double X, double Y);



int main(void) {
  double a, u, P, d, X;
  double diff;
  double div;
  double squared;
  double d2;

double pi2;
double sqrt1;
double multiply1;
double fraction;// referring to 1/a*sqrt(2pi)
double expo;
  int tests;
  a=1.14;// "a" is the sigma.
  u=10.71;//"u" is the Mu.
while(tests){//while loop for infinite loops.
printf("Probability of X given Mu= %lg and Sigma= %lg \n\n",u, a);
printf("Enter the X values: ");
scanf("%lf",&X);
//Steps to find what "d" is equal to
diff=sub(X,u);//X-u.
div=divide(diff,a);//(x-u)/a
squared=pow(div,2);//((X-u)/a)^2
d=divide(squared,2);//((X-u)/a)^2)/2
d2=multiply(-1,d);//multiplies d*-1 to get -d for the exp=e^-d formula.

//steps to find P using the X value given by the user and the value found for "d"
pi2= multiply(2,Pi);// 2*pi
sqrt1= sqrt(pi2);// square root of 2*pi
multiply1=multiply(a,sqrt1);// sigma* square root of 2*pi
fraction=divide(1,multiply1);
expo=exp(d2);//e^-d
P=multiply(fraction,expo);// (1/a*sqrt(2pi))*expo
printf("\nThe probability of %lg in this distribution is \n%lg\n", X,P);
printf("-------------------\n");
}
return 0;}