On Thu, Jun 11, 2026 at 07:58:53PM +0800, Qian Yun wrote:
> On 6/11/26 7:44 PM, Waldek Hebisch wrote:
> >
> > AFAICS this is essentially the same as NAG version:
> >
> > x:% = y:% == x =$Rep y
> >
> > (where Rep is doing calculation which you expanded inline)
> > which was changed to current one because the simpler thing
> > is sometimes incorrect.
> >
>
> > Look at commit 3255808d742077bc16f5ab47d658be3e80dcdf16
>
> It is not the same as old one, because I'm doing
> multiplication in EXPR, not Rep. So 'reduc' is applied.
>
> In theory, I didn't missing anything, right?
I see, mutiplication in EXPR is probably good enough to pass
our existing tests, but this does not look right. Note that
we may have nested roots and mutiplying two roots may introduce
new denominators.
In general, representation of Expression is only normal: when
result of an operation is 0 it will give 0 at representation
level, but equal expressions may have different representations.
AFAICS the following should be OK:
algreduc((numer(x)*$Rep denom(y) -$Rep numer(y)*$Rep denom(x))::%,
commonk(x, y)) =$Rep 0
--
Waldek Hebisch
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