Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!asuvax!enuxha!hurwitz
From: hurwitz@enuxha.eas.asu.edu (Roger A. Hurwitz)
Newsgroups: comp.lang.c
Subject: Re: fibonacci Numbers
Summary: Fibonacci Formula
Keywords: Fibonacci Numbers - routines?
Message-ID: <3019@enuxha.eas.asu.edu>
Date: 13 Apr 91 06:01:45 GMT
References: <1991Apr12.051844.15063@milton.u.washington.edu>
Organization: Arizona State University, Tempe, AZ
Lines: 22

In article <1991Apr12.051844.15063@milton.u.washington.edu>, amigo@milton.u.washington.edu (The Friend) writes:
> 
>      Can someone send me source code for a routine to calculate 
> Fibonacci numbers to _x_ (x being input from user)? Additionally it'd
> be great if this found the PRIME numbers in the set. It could print its
> results as it went through (if that makes it any easier).

I picked up the following nifty formula from somewhere for calculating
any Fibonacci number in the sequence:

#include <math.h>
#define SQRT5 2.2360679775

main()
{
    double x, fib;
        .
	.
    fib = (pow((1.0 + SQRT5) / 2.0, x) - pow((1.0 - SQRT5) / 2.0, x)) / SQRT5;
}

I'm afraid I can't help you on the prime number question.  =^)