#11912: Clarify simplify_radical and Maxima's radcan
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Reporter: kcrisman | Owner: mvngu
Type: enhancement | Status: new
Priority: minor | Milestone: sage-5.11
Component: documentation | Resolution:
Keywords: | Work issues:
Report Upstream: N/A | Reviewers:
Authors: | Merged in:
Dependencies: | Stopgaps:
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Description changed by mjo:
Old description:
> We use Maxima's
> [http://maxima.sourceforge.net/docs/manual/en/maxima_9.html#Item_003a-
> radcan radcan] (warning - link may change) for {{{simplify_radical}}}.
> The documentation claims
> {{{
> Simplifies expr, which can contain logs, exponentials, and radicals, by
> converting it into a form which is canonical over a large class of
> expressions
> and a given ordering of variables; that is, all functionally equivalent
> forms
> are mapped into a unique form. For a somewhat larger class of
> expressions,
> radcan produces a regular form. Two equivalent expressions in this class
> do
> not necessarily have the same appearance, but their difference can be
> simplified by radcan to zero.
>
> For some expressions radcan is quite time consuming. This is the cost of
> exploring certain relationships among the components of the expression
> for
> simplifications based on factoring and partial-fraction expansions of
> exponents.
> }}}
> but it can be really hard to tell exactly what this all means. See
> [http://ask.sagemath.org/question/767/simplification-errors-in-simple-
> expressions this ask.sagemath.org question] and #8497, to which this is a
> followup.
New description:
We use Maxima's
[http://maxima.sourceforge.net/docs/manual/en/maxima_9.html#Item_003a-
radcan radcan] (warning - link may change) for {{{simplify_radical}}}.
The documentation claims
{{{
Simplifies expr, which can contain logs, exponentials, and radicals, by
converting it into a form which is canonical over a large class of
expressions
and a given ordering of variables; that is, all functionally equivalent
forms
are mapped into a unique form. For a somewhat larger class of expressions,
radcan produces a regular form. Two equivalent expressions in this class
do
not necessarily have the same appearance, but their difference can be
simplified by radcan to zero.
For some expressions radcan is quite time consuming. This is the cost of
exploring certain relationships among the components of the expression for
simplifications based on factoring and partial-fraction expansions of
exponents.
}}}
but it can be really hard to tell exactly what this all means. See
[http://ask.sagemath.org/question/767/simplification-errors-in-simple-
expressions this ask.sagemath.org question] and #8497, to which this is a
followup.
The plan is to rename `simplify_radical()` to `radcan()` to match the
upstream name. We can then alias `simplify_radical()` to `radcan()`, and
deprecate the `simplify_radical()` name.
Afterwards we can attempt to clarify the docs, and provide more examples
of `radcan()`'s usage. We should provide both cautionary examples from our
tickets, and some of the use cases that Dr. Fateman has described.
--
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11912#comment:2>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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