Extending assignment Was: Functions with any number of arguments

Lisp not needed:

if l = [] then ...
On Jan 19, 2012 8:17 AM, "Alexander Klimov" <alserkli at inbox.ru> wrote:

> On Sun, 15 Jan 2012, Aleksas Domarkas wrote:
> > How  in Maxima define functions with any number of arguments ?
> >
> > For example, i need function MIN(arg1,arg2, ...)
> > MIN(2) => 2
> > MIN(3,4) =>3
> > MIN(2/3,1/2,sqrt(2)/2) => 1/2
>
>  MIN([args]) := block([m:first(args)],
>                      for i in rest(args) do m:min(m,i),
>                      m);
>
> > Other example. How define G with following properties:
> > G(n) => gamma(n)
> > G(5) => 24
> > G(a, x) => gamma_incomplete (a, x)
> > G(a, z1, z2) =>  gamma_incomplete_generalized (a, z1, z2)
>
> Use "length(args)" and "if <cond_1> then <expr_1> elseif ..."
>
>
> What I wonder, is whether there is a more efficient way to check that
> a list has empty tail than evaluate its length: I guess "empty" should
> be a built-in function:
>
>  empty(l) := block([simp:false], ?null(?cdr(l)));
>  list_min(l) := block([f:first(l),r:rest(l)],
>   if empty(r) then f else min(f, list_min(r)));
>  MIN([args]) := list_min(args);
>
> It would also be nice if "[a,b]:[1]" were not an error but instead
> assigns false (NIL) to b. This would allow to do
>
>  [a,b,c]:args;
>  if c then /* 3 args */
>  elseif b then /* 2 args */
>  else ...
>
> --
> Regards,
> ASK
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