Of course I can create an if-then procedure, where I handle all cases separately, even though that means repeating some of the code. It's not very fancy, but it gets the job done.

Because then it would just be a required parameter, and I want to remove as much of the complexity of the application as possible. More 'advanced' users might want to give their own symbols to certain parameters, but maybe not the average user.

Apart from that, though, there is the problem that the user is only allowed to specify one, because they cannot be used both at the same time in the procedure. Trying to specify both should give an error but when I have them both as ordered required parameters then it seems rather silly to produce an error.

Ah, but suppose I use S in the sequel, and that the user has not specified the symbol. In that case, S should simply be used in its place, but now it's been assigned NULL. Without unassigning it, I cannot use it. However, unassign('S') obviously leads to an error. Any ideas?

Thanks! I did not even consider the possibility of problems with 2D notation. Usually I do my programming in plain text files that I then read in Maple, so no problem there.

Just out of curiosity, why do you want such an advanced application on your smartphone? Do you really want to be typing expressions on a touchscreen? I think you could hardly see any expressions, let alone do something useful with them...

Hi,

I'm not sure how to do it in Maple but in case you are interested to learn another symbolic language, then try FORM. All its objects are by default non-commutative, and it's fast.

Best,

Fred.

The double seq seems nice. I never realized you could place if statements inside them. Pretty neat.

What I meant with function is a mathematical function, so the second argument can be any combination of the variables, say, f(x[1],x[2]-x[1]*x[0]) or f(x[0],sqrt(2)*x[2]).

So, if my expression is

Expr:=a*f(x[0],x[2]-x[1]/r) + b*f(x[1],Pi*x[2]+x[0]) + c*f(x[2],w*x[2]^2)  

with r and w some variables, I want to get the a, b and c in the order of x[0..2]. Sorry if my description is not as "mapley" as it should be...

muchos gracias, amigos! is there any reference or guide where I can learn more about command such as frontend, curry (apart from the maple help files), which don't seem to be part of most standard guides to using maple?