Oops, I forgot to add one line of output
(3) -> distribute(%)::Float
(3) 0.7681727501_0912254214 E 418
Type: Float
Time: 0 sec
'distribute' is the operator that "undoes" 'paren'.
On 20 March 2017 at 13:32, Bill Page <[email protected]> wrote:
> The problem is just the expansion of (1+x)^10000.
>
> (1) -> )set message time on
>
> (1) -> g(x) == (1+x)^10000
> Type: Void
> Time: 0 sec
> (2) -> eval(D(g(x),x), x=0.1)
> Compiling function g with type Variable x -> Polynomial Integer
>
> Type: Polynomial Float
> Time: 3.09 (IN) + 6.74 (EV) + 0.06 (OT) = 9.89 sec
>
> In FriCAS and OpenAxiom (probably Axiom too) the correct way to avoid
> this is to treat (1+x) as a kernel via the identity operator 'paren'.
>
> (3) -> g(x) == paren(1+x)^10000
> Compiled code for g has been cleared.
> 1 old definition(s) deleted for function or rule g
> Type: Void
> Time: 0 sec
> (4) -> eval(D(g(x),x), x=0.1)
> Compiling function g with type Variable x -> Expression Integer
> 9999 ,
> (4) 10000.0 (1.1) %paren (1.1)
>
> Type: Expression Float
> Time: 0.09 (IN) + 0.05 (OT) = 0.14 sec
>
> The only trouble here is that neither FriCAS nor OpenAxiom know how to
> differentiate this operator. This can be fixed with the following
> patch:
>
> https://github.com/billpage/fricas/commit/04c1f9b2d5eb4ece95c6f5dded46a72181cecb06
> https://github.com/billpage/fricas/commit/04c1f9b2d5eb4ece95c6f5dded46a72181cecb06.patch
>
> (1) -> g(x) == paren(1+x)^10000
> Type: Void
> Time: 0 sec
> (2) -> eval(D(g(x),x), x=0.1)
> Compiling function g with type Variable(x) -> Expression(Integer)
>
> 9999
> (2) 10000.0 (1.1)
> Type: Expression(Float)
> Time: 0.04 (IN) + 0.00 (EV) + 0.12 (OT) = 0.16 sec
>
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