Fibonacci with no recursion for fun

[HAL 9000]

I made a non recursive Fibonacci function in C for fun because it can't solve 100 fast with recursion.
Did anyone else besides me do it this way

#include<stdio.h>

/*prototypes*/
double fib(int n);

int main(void)
{
	int i;
	
	for(i = 0;i <= 100;++ i)
	{
		printf("%1.0f \n",fib(i));
	}

	return 0;
}

/*non recursive fibonacci function*/
double fib(int n)
{
	double prev = -1;
	double result = 1;
	double sum;
	int i;
	
	for(i = 0;i <= n;++ i)
	{
		sum = result + prev;
		prev = result;
		result = sum;
	}
	
	return result;
}

[samy]

Hi HAL 9000!

Your code looks good. I have not tried your code but it seems to be working. I want to ask a question (just for sharing fun along with you) as to how long your code can extent i.e until what number.

[WingedPanther]

I tend to do factorials, permutations, and combinations in loops for the same reason.

[samy]

Hi WingedPanther!

Would you like to share the fun with us by giving the program for factorials, permutations, and combinations?

[John]

Originally Posted by HAL 9000

I made a non recursive Fibonacci function in C for fun because it can't solve 100 fast with recursion.
Did anyone else besides me do it this way

#include<stdio.h>

/*prototypes*/
double fib(int n);

int main(void)
{
	int i;
	
	for(i = 0;i <= 100;++ i)
	{
		printf("%1.0f \n",fib(i));
	}

	return 0;
}

/*non recursive fibonacci function*/
double fib(int n)
{
	double prev = -1;
	double result = 1;
	double sum;
	int i;
	
	for(i = 0;i <= n;++ i)
	{
		sum = result + prev;
		prev = result;
		result = sum;
	}
	
	return result;
}

A few months ago, I posted this:

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <math.h>
using namespace std;
 
//Non-recrusive: O(1)
unsigned long fib(int n)
{
     return (1/sqrt(5)) * (pow(((1 + sqrt(5)) / 2), n) - pow(((1 - sqrt(5)) / 2), n));
}
 
//Recrusive: O(n)
unsigned long fib2(int n)
{
    if(n <= 2) return 1;
    else return fib2(n - 1) + fib2(n - 2);
}
 
//Iterative: O(n)
unsigned long fib3(int n)
{
    int u = 0;
    int v = 1;
    int i, t;
 
    for(i = 2; i <= n; i++)
    {
        t = u + v;
        u = v;
        v = t;
    }
    return v;        
} 

[WingedPanther]

Originally Posted by samy

Hi WingedPanther!

Would you like to share the fun with us by giving the program for factorials, permutations, and combinations?

int factorial(int n){
  int fact=1;
  for (int i=1;i<=n;i++) fact*=i;
  return fact;
}

int permutation(int n,r){
  int perm=1;
  for (int i=n-r+1;i<=n;i++) perm*=i;
  return perm;
}

int combination(int n,r){
  return permutation(n,r)/factorial(r);
}

[samy]

Hi WingedPanther!

Your code is awesome. I think you have a great mind.

Good going.

[WingedPanther]

It's a side-effect of being a mathematician: math algorithms come REALLY easily to me.

[samy]

Hi WingedPanther!

I think you love mathematics. Have you tried some thing like derivatives or integrations, sine, cosine, etc.

[WingedPanther]

I've got a master's in math... yes, I love math