Re: User defined functions: How to program &n-variables?

[Jack Brennen <jfb@brennen.net>]

Not an exact parallel to issquare() or the other builtins, but
you could try passing the name as a string:

? foo(foo_a,foo_b=0)= {
  type(foo_b)=="t_STR" && eval(concat(foo_b,"=floor(foo_a^2)"));
  return(foo_a^2);
}
? foo(11.5)
132.25000000000000000000000000000000000
? foo(11.5,"zyx")
132.25000000000000000000000000000000000
? zyx
132

This is pass-by-name, rather than pass-by-reference, but might
work for you.  The main limitation is that these won't work
because of name-space issues:

foo(N,"foo_a")
foo(N,"foo_b")

But if you make the foo() parameter names obscure enough, you can
reduce the chance of a name collision to practically zero.

On 3/8/2012 9:18 AM, Thomas Nordhaus wrote:
> Hello!
> I'd like to do something similar as in the issquare-function: How do I
> code this? For example: I want to program a function foo such that
> y=foo(x) yields y=x^2 and y=foo(x,&n) yields y=x^2 and n=floor(x^2).Is
> there a reference that explains proramming of user defined functions in
> depth?
>
> Thanks in advance,
> Thomas Nordhaus