RE: [Dev-C++] Efficiency

[Williams, T. W. <TIM...@sa...>]

The fibonacci sequence is given alot as an introduction to recursion so that
one isn't first learning recursion at the same time they're learning how to
navigate BTree.  That being the case, I assumed he was constrained to
solving the problem with recursion and I just gave him a more efficient way
to do it.  I also don't see any significant performance difference between
our two solutions, did you?   

>>(, and btw. you need more variables ...).
what's that about?

--tim

> -----Original Message-----
> From: St0fF 64 [mailto:st...@gm...]
> Sent: Tuesday, November 13, 2001 7:26 AM
> To: DevCPP
> Subject: Re: [Dev-C++] Efficiency
> 
> 
> HI!
> Recursive functions normally need a lot more time -> wanna 
> speed it up -
> ITERATE (do it in one for() / while() construct using only 
> ONE FUNCTION
> CALL).
> maybe I'll get it right:
> 
> int fibonacci_iterated(int max) {
>     if (max<0) {return 0;}
>     else {/*register*/ int n=0, m=1,o=1;
>             for(int i=0;i<=max;i++) {
>                 m+=n; n=o; o=m;}
>             return o;}
> }
> 
> I mean, if you use C then use it right!  I know some 
> functions are very easy
> coded recursively,
> but this implies a lot of stacking and jumping around, and 
> therefore it
> needs a lot of extra - calling - time.  So if a recursive 
> function should
> get speeded up, you have to count upwards instead of 
> downwards.  You need to
> iterate instead of recursing (, and btw. you need more variables ...).
> Hope this helps,
> St0fF.
> ----- Original Message -----
> From: "Williams, Timothy W." <TIM...@sa...>
> To: "'Mansoor Nathani'" <man...@sy...>; "Dev users"
> <dev...@li...>
> Sent: Friday, November 09, 2001 10:11 PM
> Subject: RE: [Dev-C++] Efficiency
> 
> 
> > #include <iostream.h>
> > #include <stdlib.h>
> > int fib(int z);
> > int fib_iter(int a, int b, int count);
> >
> > void main(void)
> > {
> >  int n;
> >  cout << "Enter n:\n";
> >  cin >> n;
> >  cout << "My Way...\n";
> >  cout << fib_iter(1, 0, n);
> >  cout << "\n and now your way...\n";
> >  cout << fib(n);
> >
> > }
> >
> >
> > int fib_iter(int a, int b, int count)
> > {
> >     if (count == 0)
> >        return 1;
> >     else
> >       return a+fib_iter(a+b, a, count-1);
> >
> > }
> > int fib(int z)
> > {
> > if (z==-1)
> > return 1;
> > if (z==-2)
> > return 0;
> > else
> > return (fib(z-1)+fib(z-2));
> > }
> >
> >
> > > -----Original Message-----
> > > From: Mansoor Nathani [mailto:man...@sy...]
> > > Sent: Friday, November 09, 2001 3:46 PM
> > > To: Dev users
> > > Subject: [Dev-C++] Efficiency
> > >
> > >
> > > Can any one please show me how to increase the efficiency of this
> > > recursive program?
> > >
> > > THe program is supposed to output the fibonacci sequence 
> up to a given
> > > value.
> > >
> > > I need it to output in the middle of the recursive function, but
> > > a lot of garbage gets acumulated.
> > >
> > > Any help would be appreciated.
> > >
> > > Thanks
> > >
> > > Mansoor
> > >
> > >
> > > #include <iostream.h>
> > > int fib(int z);
> > >
> > > void main(void)
> > > {
> > > int c;
> > > for (int abc=0;abc<10;abc++)
> > > cout<<fib(abc)<<endl;
> > > cin>>c;
> > > }
> > >
> > > int fib(int z)
> > > {
> > > if (z==-1)
> > > return 1;
> > > if (z==-2)
> > > return 0;
> > > else
> > > return (fib(z-1)+fib(z-2));
> > > }
> > >
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> 
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