OpenEuphoria

RE: math combinations

• Posted by Henri.Goffin at sbs.be May 27, 2002
• 422 views

There is a little weakness in the Permutation function in R. Forno's Genfunc.e.
It does not correctly manage a sequence that contains sequences as elements.
You can convince yourself with the following:
------------------------------------------
include genfunc.e
sequence S
S = {{1},2,{3,4}}
for i = 1 to 6 do		-- 6 = 3! (factorial, the number of permutations of 3
objects)
	?Permutation(S,length(S),i)
end for
----------------------------------------
But the correction seems straightforward. 
In genfunc.e (version 1.3) on line 2072, replace:
    return set[a] & Permutation(set[1..a-1] & set[a+1..len], size - 1, which)
with:
    return {set[a]} & Permutation(set[1..a-1] & set[a+1..len], size - 1, which)


Have a nice day, all.

Henri Goffin

> -----Original Message-----
> From:	tone.skoda at siol.net [SMTP:tone.skoda at siol.net]
> Sent:	27 May, 2002 05:49
> To:	EUforum
> Subject:	Re: math combinations
> 
> 
> I figured it out now after I searched mailing list archives.
> 
> for i = 1 to 10 do
>     ?  Permutation({1, 2, 3}, 3, i)
> end for
> 
> Still an example for every function would be very nice.
> 
> ----- Original Message -----
> From: <tone.skoda at siol.net>
> To: "EUforum" <EUforum at topica.com>
> Sent: Monday, May 27, 2002 5:01 AM
> Subject: Re: math combinations
> 
> 
> >
> > Thanks, but I really don't know how to use that function.
> > It would       help   if it had examples cause with examples you can see
> the
> > most clear what something does.
> >
> > Here it is with all its documentation:
> >
> > Permutation(sequence set, integer size, integer which)
> > --Returns a sequence containing the permutation with size 'size',
> > -- numbered 'which', from the set 'set'.
> > --The set is any sequence of objects, and so is the result.
> > --'which' starts at 1 and goes to the number of existing permutations
> > -- of this size.
> > --In case 'which' is out of bounds, an atom containing -1 is returned.
> >
> > ----- Original Message -----
> > From: "Derek Parnell" <Derek.Parnell at SYD.RABOBANK.COM>
> > To: "EUforum" <EUforum at topica.com>
> > Sent: Monday, May 27, 2002 4:13 AM
> > Subject: RE: math combinations
> >
> >
> > >
> > > Have a look at Ricardo Forno's general utility package in th
> contributions
> > > page. It has a Permutations function in it which sounds like it might
> work
> > > for you.
> > >
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> 
>