Re: [colorforth] Fibonacci numbers

[Peter Appelman <peter@xxxxxxxxxxxxxxxxx>]

On Wed, Nov 27, 2002 at 06:33:28PM -0500, Mark Slicker wrote:
> Hello,
> 
> Not too long ago Chuck said 'less' was obsolete. One use is in loop
> termination, decrementing a number and checking a condition. Here I
> provide a example of computing fibonacci numbers with 'less' and with
> '-if' for comparison.
> 
> With 'less':
> 
> : fib push 1 dup pop
> : f 2 less drop if drop nip ; then -1 + push swap over + pop f ;
> 
> With '-if'
> 
> : fib push 1 dup pop
> : f -2 + -if drop nip ; then 1 + push swap over + pop f ;
> 
> There is not a large difference here, but the second is clearly simpler,
> and does corespond more to the virtual machine, replacing words with
> primitive operations.
> 
> Mark
> 

Mark,

lets not stop there:

: fib push 1 dup pop -2 +
: f -if drop nip ; then push swap over + pop -1 + f ;

Regards,
Peter.


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