Hi,
On Tue, Aug 18, 2009 at 9:27 PM, William Stein<wst...@gmail.com> wrote:
>
>> ----------
>> sage: f(x) = function('f',x)
>>
>> sage: f(x).integral(x)
>> integrate(f(x), x)
>>
>> sage: f(x).integral(x^2)
>> x^2*f(x)
>> -----------
>
> Indeed, what does that mean? If forced to, I would interpret this as
>
> int f(x) d(x^2) = int f(x) 2 x dx
> = 2x integrate(f(x),x)
>
> So I think the Sage/Maxima answer of x^2*f(x) is bizarre.
>
> Matheamatica just considers this input to be invalid:
>
> sage: mathematica.eval('Integrate[f[x],x^2]')
>
> 2
> Integrate::ilim: Invalid integration variable or limit(s) in x .
>
> 2
> Integrate[f[x], x ]
>
> Unless you can give a explanation of what you want integrating wrt x^2
> to mean, I think we should also raise an error in Sage.
I tried that input out of curiosity during testing. I was expecting
a TypeError but instead I got an answer !!
I agree, we should raise an error. Ironically, in "calculus.py" the raise
error line (556) has been commented out for some reason.
-----------
elif not is_SymbolicVariable(v):
v = var(repr(v))
#raise TypeError, 'must integrate with respect to a variable'
---------
Cheers,
Golam
--~--~---------~--~----~------------~-------~--~----~
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
URLs: http://www.sagemath.org
-~----------~----~----~----~------~----~------~--~---
