--- Martin Rubey <[EMAIL PROTECTED]> wrote: > Currently, you can't. Note that you promise axiom that a1 is a > Quaternion Fraction Integer. However, you don't hold your promise...
How do I not hold it? I never told it anything about a1 except what type it is - were did I contradict this? > What you want is to make a1 a variable. Currently, there is no domain > of "Variables, which can take values only in Quaternion Fraction > Integer". Um. That's surprising, at least to me. (I suppose it wouldn't be if I understood...) Intuitively I would expect Variable to mean simply "an unspecified specific instance of a Domain/Type/what have you" with ALL domains being possible - just so long as you specify the type of the variable, e.g.: a1 : Variable(Matrix Quaternion Fraction Integer) A specific example might be with working in dimensional types: If I define F as type Force, m as type Mass, and a as type Length/Time^2 I want to be able to define m1 as type Mass and enter the expression m*a/m1 into the interperter to return a of type Length/Time^2 without having to ever specify any particular mass or acceleration. But I want that type information to be carried and used in the calculations - in fact, it is essential. > In fact, it is (or should be) a FAQ. See MathAction. I took a look at the FAQ link, but I might have missed it. I'll check again. > The point of Axioms type system is that any identifier has a typed > value. There is no such thing as a identifier that does not have a > value. > > If you type > > 5*a+a^2 > > into the interpreter, it responds with > > Polynomial Integer. But what if I want a to have a specific type, for example limit it to Quaternions only? > When you say p:=5*a+3*a^2, the identifier p refers to this > polynomial. The internal representation is something like > > [[5,a,1],[3,a,2]] > > How would you represent a generic polynomial? You need a different > domain for that. I guess I'm not following why things can't be further restricted by saying in this particulary case a is of type FOO, and therefore doing two things: 1) restricting the evaluation of the polynomial substitutions for a which are of type FOO 2) allowing algorithms to use the knowledge that for this polynomial a is restricted to some subset to make further deductions, simplifications, and otherwise provide more precise answers Sorry if this is an obviously trivial question. Cheers, CY __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Axiom-developer mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/axiom-developer
