On Sat, Feb 11, 2012 at 10:33 PM, John H Palmieri
<jhpalmier...@gmail.com> wrote:
>
>
> On Saturday, February 11, 2012 8:39:32 PM UTC-8, Michael Orlitzky wrote:
>>
>> I've started this:
>>
>> http://wiki.sagemath.org/PiecewiseSymbolicSEP
>>
>> It's basically a brain dump at this point, but I can go back and clean
>> up specific ideas now with less overhead.
>>
>> I've also added a link and a few paragraphs to the GSoC proposal.
>
> Would it also be possible and worthwhile to implement periodic functions at
> the same time? That is, you could define a function on some interval [a,b]
> (or [a,b) or ...) and declare it to be periodic with period b-a, for
> instance.
I think such functions should be implemented based on predicates
rather than intervals. Then they could support this as well as being
multi-variate, etc. Unfortunately the mod operator doesn't seem to
work with symbolics (could be adde to the SEP)
sage: x % 1
...
TypeError: unable to convert x (=x) to an integer
And we also have the ugly
sage: 0 < x < 5
0 < x
and
sage: var('y,x')
(y, x)
sage: (0 < x) & (0 < y)
...
TypeError: unsupported operand type(s) for &:
'sage.symbolic.expression.Expression' and
'sage.symbolic.expression.Expression'
Part of this SEP could be to make both of these work (if possible, the
first might be impossible due to shortcutting and bool(expr) returning
False by default). Note that if the predicates are evaluated in a
cascading manner, this wouldn't be needed as often.
Another complication is detecting boundaries (e.g. for
differentiability tests) for arbitrary predicates, but this could be
done for inequalities.
- Robert
--
To post to this group, send an email to sage-devel@googlegroups.com
To unsubscribe from this group, send an email to
sage-devel+unsubscr...@googlegroups.com
For more options, visit this group at http://groups.google.com/group/sage-devel
URL: http://www.sagemath.org
