How can I define a NARY operator?

I believe  you found a bug in rassociative or its friends:

(C1) infix("&");
(D1)                                  "&"
(C2) a & (b & c);
(D2)                              a & (b & C)
(C3) declare("&",rassociative)$

a & b is no problem, but a & (b & c) is a problem.  My commercial  Macsyma
doesn't have a problem with a & (b & c).

(C4) a & b;
(D4)                                 a & b
(C5) a & (b & c);
Wrong number of arguments to "&"
 -- an error.  Quitting.  To debug this try DEBUGMODE(TRUE);)

Maybe you can do what you want by using parenthesis to indicate grouping
and skip declaring "&" to be right associative.  For example (starting 
with a
fresh Maxima session)

(C1) infix("&");
(D1)                              "&"

/* Doesn't seem to be a problem now */

(C2) a & (b & c);
(D2)                          a & (b & C)

Additionally, you can declare a nary operator using

(C1) nary("@");
(D1)                                     "@"
(C2) a @ (b @ c);
(D2)                                 a @ (b @ C)

To give @ a formula, use (for example)

(C3) "@"([x]) := apply("*",x)^(1/length(x))$

(C4) 1 @ 2 @ 3;
                                         1/3
(D4)                                    6


Barton


wang yin <wang-y01@mails.tsinghua.edu.cn>
Sent by: maxima-admin@www.ma.utexas.edu
01/21/2003 02:08 AM

 
        To:     maxima@mail.ma.utexas.edu
        cc: 
        Subject: [Maxima] How can I define a NARY operator?


Hi,

I'm declaring an operator "&", which is INFIX, RASSOCIATIVE. I input these 
lines:

(C1) INFIX("&");

(D1)                                  "&"
(C2) DECLARE("&",RASSOCIATIVE);

(D2)                                 DONE
(C3) X&Y&5;

Wrong number of arguments to "&"
 -- an error.  Quitting.  To debug this try DEBUGMODE(TRUE);)

when I input X&Y&5, MAXIMA throw out this error. But I want to get
something like x & (y & 5)

I then define this operator as:

(C12) "&"(a,b):=(a-b)/(a*b);

                                         a - b
(D12)                           a & b := -----
                                          a b
this time I get
(C15) X&Y&5;

                                   X - Y
                                X (----- - 5) Y
                                    X Y
(D15)                           ---------------
                                   5 (X - Y)

Not an error. But I don't want to define "&" now.
How can I get rid of the error before?

If I declare "&" as NARY, I can get the answer I want.
Must I declare a NARY operator?
But the MAXIMA manual doesn't describe how to define a NARY operator.

If I define a NARY "&" as:
(C29) "&"(a,b):=a+b;

(D29)                           a & b := a + b
(C30)  x&y&5;

Too many arguments supplied to a & b:
[x, y, 5]
#0: \&(a=x,b=y)
#1: \&(a=x,b=y)
#2: \&(a=3,b=7)
 -- an error.  Quitting.  To debug this try DEBUGMODE(TRUE);)

How can I define NARY operators? 
Can anyone tell me? Thanks!

-- 
Wang Yin
DA Lab, Tsinghua University,
100084
Beijing China