Waldek Hebisch <[EMAIL PROTECTED]> writes:
> Martin Rubey wrote:
> >
> > Waldek Hebisch <[EMAIL PROTECTED]> writes:
>
> > > > +-- coefficient(p, lv, ln) views the polynomial p as a polynomial
> > > > +-- in the variables of lv and returns the coefficient of the term
> > > > +-- \spad{lv**ln}, i.e. \spad{prod(lv_i ** ln_i)}.
> > > > +
> > > > + coefficient(s: %, lv: List Var, ln: List NNI): % ==
> > > > + map(coefficient(#1, lv, ln), s)
> > >
> > > It looks that terms of resulting series have wrong degree.
> >
> > Are you sure?
> >
>
> In SparseMultivariateTaylorSeries we have:
>
> ++ This domain provides multivariate Taylor series with variables
> ++ from an arbitrary ordered set. A Taylor series is represented
> ++ by a stream of polynomials from the polynomial domain SMP.
> ++ The nth element of the stream is a form of degree n. SMTS is an
> ^^^^^^^^^^^ ^^^^^^^^
> ++ internal domain.
>
> Now, I did not check which map you use, but my guess is that it
> maps nth term of source series to nth term of target sequence.
> However coefficient lowers degree -- that is why I suspect that
> this implementation breaks invariant.
Oh, very good catch... Unfortunately, I have no idea how to cure this. Do you
have an idea? do you think lazyEvaluate from Stream might help?
Thanks,
Martin
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