Hello, I last used Axiom about 8 years ago, and I haven't kept up either with it or its forks much since then. (I'm listed as a contributor at http://www.axiom-developer.org/axiom-website/community.html). Anyway, I've since forgotten pretty all I knew (which was never much); in particular how best to manipulate types.
Just today I downloaded the source of FriCAS and compiled it. Here's my first question. I am experimenting with formal derivatives. So: f := operator 'f > y := operator 'y > f1 := D(f(x,y(x)),x) > f1 := subst(f1,D(y(x),x)=f(x,y(x))) > This looks fine so far. However, eventually I want to do some algebraic manipualtion on these (and higher) derivatives, for which it will be convenient to replace derivatives in these expressions with a simple symbol. For example: f2:=D(f1,x) > f2:=subst(f2,D(y(x),x)=f(x,y(x))) > message(unparse(f2::InputForm))$OutputForm > > > D(D(f(x,y(x)),x::Symbol),x::Symbol)+(f(x,y(x))^2*D(D(f(x,y(x)),y(x)::Symbol), > > y(x)::Symbol)+(f(x,y(x))*D(D(f(x,y(x)),y(x)::Symbol),x::Symbol)+(f(x,y(x))*D( > > D(f(x,y(x)),x::Symbol),y(x)::Symbol)+(D(f(x,y(x)),y(x)::Symbol)*D(f(x,y(x)),x > ::Symbol)+f(x,y(x))*D(f(x,y(x)),y(x)::Symbol)^2)))) > (I filched the "message" command from the Axiom newsgroup archive.) What I want to do is something like subst(f2,D(D(f(x,y(x)),x),x)=Fxx) > so that in my final expression the symbol "Fxx" will take the place of D(D(f(x,y(x)),x::Symbol),x::Symbol) in the above output expression. This is going to require some coercion... but I'm not sure how. Any ideas? Second question: the Axiom pages say that Hyperdoc is being replaced with a help browser under Firefox. I like the idea of this very much: Hyperdoc always seemed a bit clumsy to me. Is this available in FriCAS, and if so, how? Thanks, folks! -Alasdair -- You received this message because you are subscribed to the Google Groups "FriCAS - computer algebra system" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/fricas-devel. For more options, visit https://groups.google.com/groups/opt_out.
