[micaxxa]

I have to make a program that finds the value of e such that the formula used is 1+1/1!+1/2!+1/2!+1/3!+1/n!..... these terms are added till the term does not become less than 0.001.

p.s this is not my homework, I am just practicising some programming for my test, would be glad to get some help!!

#include <stdio.h>
int main(void)
{double term,den,sum,n,x;

 for(sum=0.0,n=0.0;term>0.001;n++)
 {
  if(n==0.0||n==1.0)
   {x=1.0;}
   else
   {
    x*= n;
     }

   term=1/x;
   sum+=term;

   }

   printf("%lf",sum);
   return 0;
   }

[CTphpnwb]

This:

   term=1/x;

needs to be this:

   term=1/factorial(x);

Now you need to write factorial:

int factorial(int Num)
{
 // compute factorial
}

and get rid of your if statement.

This post has been edited by CTphpnwb: 17 October 2010 - 02:51 PM

[micaxxa]

I havent studied functions yet !! , but thanks anyways. Can you tell me why this will not work properly ?

[#define]

Hi, term is not initialised. The value of term is probably zero so the for loop will not be executed.

[micaxxa]

#define, on 17 October 2010 - 03:28 PM, said:

Hi, term is not initialised. The value of term is probably zero so the for loop will not be executed.

I initialised the term it didnt help :S

[lfaivor21]

Watch out using a for loop in this way. Usually you'd want to use a while loop in this case.

for(sum=0.0,n=0.0;term>0.001;n++){
}

So the code might read instead... while term is > 0.001 keep looping. Instead of saying given n loop until term > 0.001 and then keep incrementing n. Teacher might be upset about it even if it works.

term = 1.0; //Set term to a number greater than 0.001 so the conditional holds true in the while loop for the first run.
sum = 0.0;
n = 0.0;
while(term>0.001)
{
     x = 1.0; //Covers the case when n = 0 as well! and returns x = 1 just like you'd expect.
     while(n!=0.0)
     {
          //multiply n*n-1*n-2 etc until n goes to 0. and set each step = to x
     }
     term = 1/x;
     sum +=x
     n++;
}

So instead of a separate function an easy and short nested loop would suffice just as well. Generally you'd want to use for loops to loop a number of times given by your iteration variable like i or n and not for testing for a condition and looping until it's met. Sure it can be used that way but I got docked for it in class so I'm assuming you might too.
Hope this helped!!

This post has been edited by lfaivor21: 17 October 2010 - 09:56 PM

[lfaivor21]

I made a slight booboo in the code. Here's an update.

term = 1.0; //Set term to a number greater than 0.001 so the conditional holds true in the while loop for the first run.
sum = 0.0;
n = 0.0;
iteration = 0; //Initialize an iteration variable to keep track of what n needs to be.
while(term>0.001)
{
     x = 1.0; //Covers the case when n = 0 as well! and returns x = 1 just like you'd expect.
     while(n!=0.0)
     {
          //multiply n*n-1*n-2 etc until n goes to 0. and set each step = to x
     }
     term = 1/x;
     sum +=x
     iteration++;
     n = iteration;
}

This post has been edited by lfaivor21: 17 October 2010 - 10:06 PM

[CTphpnwb]

You were closer in your first post.
Here it is using a function:

#include <stdio.h>
#include <iostream>
using namespace std;
int fact( int number);

int main()
{
	double term,sum;
	int n, x;
	term = 1;
	sum = 0;
	n = 0;
	while(term>0.001)
	{
		x = fact(n);
		term=1.0/x;
		sum+=term;
		n++;
	}
	
	cout << "e: \t" << sum << endl;
	return 0;
}

int fact( int number)
{
	int myfact = 1;
	for (int i = number; i > 1; i--) {
		myfact *= i;
	}
	return myfact;
}

Put aside the function call and think about how this compares to yours. Do you see how this is similar to yours, and where the logic is different?

[lfaivor21]

If you were talking about my posts.. yeah I see it In my first post I was iterating n but should have initialized another variable for inside the nested loop. The second post worked with my initial logic with using n inside the nested loop while keeping track of iterations... which is where my first post was lacking. Oh and I set the sum equal to x instead of term. Thanks for catching my mistakes.

This post has been edited by lfaivor21: 18 October 2010 - 10:37 AM

[micaxxa]

Thankyou guys, I see for loop is usually good for making stars and all. I have just become too addicted to for loops for some odd reason that even though I know about while, I try to use for loop all the time =___=