simplify inverse_erf(erf(x))



Where would I add a failing unit test?

Do you all want to improve the property system to know about inverse
domains, or limit the focus to erf/inverse_erf?


On Mon, Dec 30, 2013 at 3:46 AM, Barton Willis <willisb at unk.edu> wrote:

> Incidentally,  the inverse to erf is recorded on the property list of %erf
>
>    (%i75) :lisp(get '%erf '$inverse)
>    %INVERSE_ERF
>
> The solve function examines  the property list of %erf to solve things
> such as
>
>    (%i1) solve(erf(x)=7,x);
>    (%o1) [x=inverse_erf(7)]
>
> The general simplifier does not routinely look for inverse on the property
> list. Actually, the property list mechanism doesn't have a way to check
> that for  the appropriate domain.
>
> --Barton
>
> ________________________________________
>
> Buck Golemon <buck.2019 <at> gmail.com> writes:
>
> > (%i12) solve(erf(x) = erf(y), x);
> >
> > (%o12)                     [x = inverse_erf(erf(y))]
> >
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