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Re: [Axiom-mail] Failure to simplify trig functions of simple rational m
From: |
Martin Rubey |
Subject: |
Re: [Axiom-mail] Failure to simplify trig functions of simple rational multiples of %pi |
Date: |
Wed, 26 Aug 2009 13:45:08 +0200 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.3 (gnu/linux) |
Dan Hatton <address@hidden> writes:
> Further to the earlier bits of this thread, I'd been hoping to be able
> to produce the answer "1" with something like
>
> l:Union(Variable l,Integer)
> simplify(cos(2*%pi*l))
> but instead I just get the cosine expression quoted back at me - is
> there some other function I should use instead of simplify() for this,
> please?
The short answer is, unfortunately, "no". Axiom (FriCAS, OpenAxiom)
currently does not support "assumptions" like "assume that l is an
integer".
The declaration
(1) -> l:Union(Variable l,Integer)
Type: Void
demonstrates a frequent misunderstanding of axiom's types: what you
really tell axiom here is that the type of l is
Union(Variable l,Integer)
which means that l can hold either the variable "l", or a *concrete*
integer:
(2) -> l := -42
(2) - 42
Type: Union(Integer,...)
(3) -> l := 'l
(3) l
Type: Union(Variable(l),...)
There is (currently) no such type as "symbolic integer".
There has been a lot of discussion on how to implement what you want,
but as far as I know, nobody is working on it. Would you be interested?
Martin