#2697: [with patch, needs review] allow integration without explicit variable
declaration
-------------------------+--------------------------------------------------
Reporter: was | Owner: kcrisman
Type: enhancement | Status: new
Priority: major | Milestone: sage-3.2.1
Component: calculus | Resolution:
Keywords: |
-------------------------+--------------------------------------------------
Changes (by kcrisman):
* owner: was => kcrisman
* summary: [with patch, negative review] allow integration without
explicit variable declaration => [with patch,
needs review] allow integration without
explicit variable declaration
Comment:
Replying to [comment:3 robertwb]:
Posting (final? I hope) version of patch, based on 3.2.alpha0. Passed
doctests for calculus.py once, all other times it timed out for me, but I
do not believe it changes pre-existing correct behavior.
> I'm getting
>
> {{{
> sage: integrate(sin(x), pi, 2*pi)
> ------------------------------------------------------------
> Traceback (most recent call last):
> File "<ipython console>", line 1, in <module>
> File "/Users/robert/sage/sage-3.1.3/local/lib/python2.5/site-
packages/sage/calculus/functional.py", line 254, in integral
> return f.integral(*args, **kwds)
> File "/Users/robert/sage/current/local/lib/python2.5/site-
packages/sage/calculus/calculus.py", line 2586, in integral
> raise TypeError, 'only one endpoint given'
> TypeError: only one endpoint given
> }}}
>
Turns out that this actually comes from the original code, where the
second item was turned into a variable in case someone used some already-
in-use identifier for the variable; the problem was that it turned things
like e and pi into variables.
> Rather than catching the error that, say, 0 is not a valid variable
name, perhaps one should look at the number of variables passed to
determine how to integrate. E.g.
>
> {{{
> sage: integrate(sin(x)) # 0 args, implicit indefinite
> cos(x)
> sage: integrate(sin(x), y) # 1 arg, explicit indefinite
> sin(x)*y
> sage: integrate(sin(x), pi, 2*pi) # 2 args, implicit definite
> -2
> sage: integrate(sin(x), y, pi, 2*pi) # 3 args, explicit definite
> pi*sin(x)
> }}}
Good idea! In the end, though, it was easier for me to just jury-rig the
code as is. When I make my own functions I try to do that sort of
planning, but I don't feel confident enough (or have enough time) to
completely change the way this type of code works. Hopefully my final
solution is still pretty good, though; it does all of the above, except
you will have to declare y beforehand (I couldn't find a way around that),
and the first integral is -cos(x) :)
As a bonus, I was finally able to figure out how to do this, which now
works:
{{{
sage: integrate(sin,0,pi)
2
}}}
That alone is worth it for me.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/2697#comment:4>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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