Problem with simple Factorial Estimation

This is a discussion on Problem with simple Factorial Estimation within the C Programming forums, part of the General Programming Boards category; The assignment was to create a program to estimate the factorial of a positive integer using Gosper's formula. I changed ...

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    Problem with simple Factorial Estimation

    The assignment was to create a program to estimate the factorial of a positive integer using Gosper's formula. I changed it to display intermediate values to find the error, and it looks like root_part is only using the "2n" and not the full "2n + 1/3", but I can't figure out why it's doing that. Reversing them had no effect either. The rest seems accurate given the wrong root_part value.

    Any help would be greatly appreciated.

    Code:
    #include <stdio.h>
    #include <math.h>
    
    #define PI 3.14159265
    
    int
    	main(void)
    {
    	double  n,
    		root_part,
    		root_solved,
    		n_factorial;
    	printf("Enter a positive integer> ");
    	scanf("%lf", &n);
    
    	root_partial = (1 / 3) + (2 * n);
    	printf("Variable root_part = %f \n", root_part);
    
    	root_solved = sqrt(root_part * PI);
    	printf("Variable root_solved = %f \n", root_solved);
    
    	n_factorial = (pow(n,n) * exp(-n)) * root_solved;
    	printf("%.0f! equals approximately %.5f \n", n, n_factorial);
    
            return(0);
    }

  2. #2
    ATH0 quzah's Avatar
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    1/3 = 0
    1.0/3.0 = .333333~


    Quzah.
    Hope is the first step on the road to disappointment.

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    Thanks for the quick reply. Fixed everything

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    Quote Originally Posted by Arthurdent View Post
    Thanks for the quick reply. Fixed everything
    Ahhh... 42.... another Hitchiker's Guide fan!

    Welcome to the forums.

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    Programming Wraith GReaper's Avatar
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    Quote Originally Posted by CommonTater View Post
    Ahhh... 42.... another Hitchiker's Guide fan!

    Welcome to the forums.
    Nah, it's just a coincidense... ( But a good book! )
    Devoted my life to programming...

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    Quote Originally Posted by Sipher View Post
    Nah, it's just a coincidense... ( But a good book! )
    Darn... I was so looking forward to the "He's got a TOWEL... run away, run away!" line.

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    Programming Wraith GReaper's Avatar
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    Quote Originally Posted by CommonTater View Post
    Darn... I was so looking forward to the "He's got a TOWEL... run away, run away!" line.
    lol, it's been years since I read this book, yet I still remember it. The author's way of comparing Earth's with Milky Way's bureaucracy was, by my opinion, hilarious! Hehe, the symmenty of events is also outstanding!
    Devoted my life to programming...

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    Quote Originally Posted by Sipher View Post
    lol, it's been years since I read this book, yet I still remember it. The author's way of comparing Earth's with Milky Way's bureaucracy was, by my opinion, hilarious! Hehe, the symmenty of events is also outstanding!
    Read the book and have the movie... frankly I liked the movie better... "I'm so depressed"...

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