Martin Rubey wrote:
>
> Dear Waldek,
>
> I do not really understand your patch to isExpt.
>
> isExpt:(%,OP) -> Union(Record(var:K,exponent:Z),"failed")
> ++ isExpt(p,op) returns \spad{[x, n]} if \spad{p = x**n}
> ++ and \spad{n <> 0} and \spad{x = op(a)}.
> isExpt:(%,SY) -> Union(Record(var:K,exponent:Z),"failed")
> ++ isExpt(p,f) returns \spad{[x, n]} if \spad{p = x**n}
> ++ and \spad{n <> 0} and \spad{x = f(a)}.
>
IMHO op(a) is short way of saying that op has exactly one argument
(we can put longer version in documantation comment). AFAICS
existing code assumes that after isExpt(p, op) x has correct
number of arguments. However, it is possible to create kernels
with different number of arguments (as the testcase shows).
> >From the documentation I'd think that
>
> (1) -> p := sum(1/i, i=0..n)
>
> n
> --+ 1
> (1) > -
> --+ i
> i= 0
> Type: Union(Expression(Integer),...)
>
> (2) -> isExpt(p^2, operator first kernels p)
>
> n
> --+ 1
> (2) [var= > -,exponent= 2]
> --+ i
> i= 0
> Type: Union(Record(var: Kernel(Expression(Integer)),exponent: Integer),...)
>
> But it seems that after the patch, this is not the case anymore.
>
first kernels p has 5 arguments, so fails the test. In all places
where isExpt is used for operators which have different number of
arguments than 1 we need to insert explicit tests for operator and
number of arguments.
--
Waldek Hebisch
[EMAIL PROTECTED]
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