Hi Alex,
On Sun, 7 Jun 2009 11:31:26 -0700 (PDT)
Alex Raichev <[email protected]> wrote:
>
> Hi all:
>
> Upon upgrading to Sage 4.0, i can no longer make a dictionary with
> derivatives as keys (see below). Can someone please fix this?
> ----------------------------------------------------------------------
> | Sage Version 4.0, Release Date: 2009-05-29 |
> | Type notebook() for the GUI, and license() for information. |
> ----------------------------------------------------------------------
> sage: X= var('x,y')
> sage: f= function('f',*X); f
> f(x, y)
> sage: for x in X:
> ....: diff(f,x)
> ....:
> D[0](f)(x, y)
> D[1](f)(x, y)
> sage: d= {}
> sage: for x in X:
> ....: d[diff(f,x)] = 1
> ....:
<snip>
> /Applications/sage/local/lib/python2.5/site-packages/sage/rings/
> complex_interval_field.pyc in __call__(self, x, im)
> 286
> 287 try:
> --> 288 return x._complex_mpfi_( self )
> 289 except AttributeError:
> 290 pass
>
> /Applications/sage/local/lib/python2.5/site-packages/sage/symbolic/
> expression.so in sage.symbolic.expression.Expression._complex_mpfi_
> (sage/symbolic/expression.cpp:5484)()
<snip>
> /Applications/sage/local/lib/python2.5/site-packages/sage/symbolic/
> expression_conversions.pyc in derivative(self, ex, operator)
> 344 NotImplementedError: derivative
> 345 """
> --> 346 raise NotImplementedError, "derivative"
> 347
> 348 def arithmetic(self, ex, operator):
>
> NotImplementedError: derivative
>
I opened a ticket for this:
http://trac.sagemath.org/sage_trac/ticket/6243
As I wrote on the ticket, I believe the correct fix is to change pynac
to handle more general numerical approximations. I will try to get this
done until the next release.
There might be an easier fix by implementing the derivative method in
sage.symbolic.expression_conversions.Converter. Maybe Mike can comment
on that.
Thanks.
Burcin
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