C Y <[EMAIL PROTECTED]> writes: > Question came up on IRC, and I'm curious. Given the following: > > AXIOM Computer Algebra System > Version: Axiom (September 2006) > Timestamp: Saturday September 9, 2006 at 11:29:25 > ----------------------------------------------------------------------------- > Issue )copyright to view copyright notices. > Issue )summary for a summary of useful system commands. > Issue )quit to leave AXIOM and return to shell. > ----------------------------------------------------------------------------- > > Re-reading compress.daase Re-reading interp.daase > Re-reading operation.daase > Re-reading category.daase > Re-reading browse.daase > (1) -> > (1) -> a1 : Quaternion Fraction Integer > > Type: Void > (2) -> a2 : Quaternion Fraction Integer > > Type: Void > (3) -> a3 : Quaternion Fraction Integer > > Type: Void > (4) -> a4 : Quaternion Fraction Integer > > Type: Void > (5) -> a1 > 5) -> > a1 is declared as being in Quaternion Fraction Integer but has not > been given a value. > (5) -> m := matrix[[a1,a2],[a3,a4]] > 5) -> > a1 is declared as being in Quaternion Fraction Integer but has not > been given a value. > (5) -> > > Why isn't this allowed? I want a1->a4 to be variables without assigned > value, and I want to create a symbolic matric where all I know about > the entries is their type, in order to do general solving operations. > How would I set this up correctly in Axiom?
Currently, you can't. Note that you promise axiom that a1 is a Quaternion Fraction Integer. However, you don't hold your promise... 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". In fact, it is (or should be) a FAQ. See MathAction. 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. 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. Martin _______________________________________________ Axiom-developer mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/axiom-developer
