Type control

[Han]

(02-23-2015 04:51 PM)salvomic Wrote:  

(02-22-2015 04:37 PM)Han Wrote:  In CAS, typing: a,b,c,d creates a list. That's just how the CAS environment parses a sequence of objects separated by a comma. So in a CAS program,

f(a,b,c,d)

can be considered as a function that takes 4 separate arguments named a,b,c, and d, or f can be considered as a function that takes a single argument: a list consisting of 4 items.

Han,
if I input [a,b], there is a way (in CAS) to tell the program that this input should be a matrix or vector and *not* a list? or other trick to do that?
In my program for Wronskian I would like threat only input like [x, x^2, ...] not also {...} or x,x^2,... if it's possible.

Thank you!

If you're trying to do some sort of dynamic input, then your function should be only defined as a function of a single variable (a list). For example:

Code:

#cas
myfunc(v):=
BEGIN
  local s;
  s:=SIZE(v);
  IF s>4 THEN RETURN("Too many arguments"); END;

  CASE
    IF s==1 THEN
      IF TYPE(v(1))<>4 THEN RETURN("First argument must be vector"); END;
      // and so on...
    END;

    IF s==2 THEN
      // etc.
    END;
  END;

END;

Note that in CAS, TYPE() and type() are two different functions. In non-CAS programs, there is only one "type" command -- the non-CAS one. In non-CAS programs, whether you use TYPE() or type(), either one will be interpreted as TYPE(). CASE vs case, RETURN() vs return, are among many differences you will have to learn.