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# Fibonnaci

 P: n/a Im trying to find any code in C developed to calculate the fibonnacci series with or without functions. I need a code example so I can studied and see how it works. Dec 9 '05 #1
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 P: n/a On 2005-12-09, MARQUITOS51 wrote: Im trying to find any code in C developed to calculate the fibonnacci series with or without functions. I need a code example so I can studied and see how it works. If you're cheating on homework, ask for something less obvious than code examples. #include double fibon(double n) { return ( pow(1.6180339887498948482045868343656381177203L,n) - pow(-.6180339887498948482045868343656381177203L,n) )/2.2360679774997896964091736687312762354406L; } Good luck explaining to your instructor how this works. [If you're not, you'll need to give people more to work with to show that you understand the problem and also give your best effort and show what code you've tried that doesn't work] Dec 9 '05 #2

 P: n/a MARQUITOS51 said: Im trying to find any code in C developed to calculate the fibonnacci series with or without functions. I need a code example so I can studied and see how it works. The Fibonacci series can be defined as f(0) = 0, f(1) = 1, and f(n) = f(n - 1) + f(n - 2) for n > 1. So it goes like this: 0, 1, 1, 2, 3, 5, 8, 13, etc. Think about how you would implement this recursively. Hint: look at the above definition. Write it. See how slow it is? Find out why. Hint: use printf. Now think about how you could make it a lot faster. Hint: think about arrays. Now see if you can avoid the need for an array by writing this iteratively instead of recursively. -- Richard Heathfield "Usenet is a strange place" - dmr 29/7/1999 http://www.cpax.org.uk email: rjh at above domain (but drop the www, obviously) Dec 9 '05 #3

 P: n/a Richard Heathfield wrote: MARQUITOS51 said: Im trying to find any code in C developed to calculate the fibonnacci series with or without functions. I need a code example so I can studied and see how it works. [...] Now see if you can avoid the need for an array by writing this iteratively instead of recursively. Do you mean Q-Matrix? If not, that's one more thing the OP might want to check out. Dec 9 '05 #4

 P: n/a On 2005-12-09, Richard Heathfield wrote: Write it. See how slow it is? Find out why. Hint: use printf. Now think about how you could make it a lot faster. Hint: think about arrays. All that's needed to change the worst-case performance to linear is a two-element cache. Dec 9 '05 #5

 P: n/a "Jordan Abel" wrote in message news:sl********************@random.yi.org... On 2005-12-09, Richard Heathfield wrote: Write it. See how slow it is? Find out why. Hint: use printf. Now think about how you could make it a lot faster. Hint: think about arrays. All that's needed to change the worst-case performance to linear is a two-element cache. I think Richard tryed to explain the process... how to move from a top down, recursion-based solution to a memoized recursion, and then to a bottom-up solution (building that same array that was used for memoization from 0 to n). This is infact the best you can do if you need to keep all of the first n Fibonacci numbers - it is unclear if the OP needs this, or he just wants to write them out. Also, your comment is covered in the last "idea" Richard gives. Dec 9 '05 #6

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