Thread: Fibonacci Sequence

You ... could, I suppose. It's a bit tricky, in that you have to know ahead of time (that is, before the user types anything at all) how long the string is going to be, and you don't. Otherwise, you go back to getting memory on-the-fly. (Same thing for trying to store all the answers in an array -- you won't know when you compile the program how big your array is going to need to be.)

PS: I'm guessing you type your posts in a word processing program before posting? Not a bad idea, but could you maybe turn off auto-hy-phen-ate?

Originally Posted by Dogmasur

Sorry, I'll stop hyphenating. I'm not using a word processor. I was just hyphenating within the window given on this forum. I should preview my posts before posting. Thx for the heads up.

I keep hearing scanf is bad and using getchar () to wait for an enter key press is bad. Is scanf safe to use here, since I am receiving a simple integer and how do I properly code to wait for a press of the enter key?

I would say that when you are working on your own small projects, like this, that using scanf and other 'unsafe' things are ok. But it is good to be aware of their limitations if you tackle something larger.

As for the fibonacci sequence, I like the recursive solution because of it's simplicity and elegance. Learning a recursive approach is valuable even if it is not always the most optimal performance wise.

I'm going to try to put this together with what knowledge I have and can gather from some "light" reading and then put it out for you all to laugh ( I mean comment) at.



Thx all.

simple, just include math.h , and than:

result = (1/sqrt(5))*((1+sqrt(5))/2)^n-(1/sqrt(5))*((1-sqrt(5))/2)^n ;

of course n is the variable...

i've learned this, this week in college.

Originally Posted by PkD

simple, just include math.h , and than:

result = (1/sqrt(5))*((1+sqrt(5))/2)^n-(1/sqrt(5))*((1-sqrt(5))/2)^n ;

of course n is the variable...

i've learned this, this week in college.

I was going to go with a much simpler a+b=c, where I would simply redefine the variables with each pass through my loop.

What you're getting into is Binet's formula, which might be a bit excessive for what I need. I have some understanding of mathematics and Fibonacci recursion's similarity to the generating polynomial of the recursion. I was asking more about how to code my program than how to compute the variables involved. Sorry if I wasn't clear and thanks for your input.

Originally Posted by PkD

simple, just include math.h , and than:

result = (1/sqrt(5))*((1+sqrt(5))/2)^n-(1/sqrt(5))*((1-sqrt(5))/2)^n ;

of course n is the variable...

i've learned this, this week in college.

I reread through the posts and thought my reply to you sounded snooty. I just wanted to apologize for that and let you know it wasn't meant to sound rude.

It 's ok.

I've just posted the Binet's formula because it's a curiosity, of course it slow down the PC , but if the user whats a number very big,maybe is it better use the formula? or 0+1+1+2+3+5+8+13+21+... ? .

thats it!