#2452: [with patch, needs review] Heaviside step function, Dirac delta needed
-------------------------+--------------------------------------------------
Reporter: gfurnish | Owner: gfurnish
Type: enhancement | Status: assigned
Priority: critical | Milestone: sage-4.1
Component: symbolics | Keywords:
Reviewer: | Author:
Merged: |
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Comment(by gmhossain):
Thanks David,
> The testing didn't reveal any failures related to the patch. However,
I'm also wondering about
> this output:
{{{
sage: f(x) = heaviside(x)+dirac_delta(x)
sage: f(1)
dirac_delta(1) + heaviside(1)
}}}
It seems, you have hit a bug in new symbolics. The similar non-evaluation
of symbolic function is happening even with other functions such as sin,
cos.
I posted this issue here
http://groups.google.com/group/sage-
devel/browse_thread/thread/3936d1290ee933a6
Burcin wrote that this is a bug and it is to be fixed in the new version
of pynac.
>
{{{
sage: f = heaviside+dirac_delta
...
TypeError
}}}
>
It seems in new symbolics, arithmetic of bare-bone functions is no-longer
allowed.
For example, if I try
{{{
f = sin + cos
}}}
then I get the same error.
> I don't see a problem with the integral methods but I'd prefer definite
integrals over indefinite ones.
> In any case,
{{{
sage: dirac_delta.integral(0)
heaviside(0)
}}}
> seems odd.
I agree this is odd. I have removed the integral methods from this patch.
Integration algorithm
that I am implementing will do both definite and indefinite integrals
involving these functions.
So I guess, it is better to avoid code-duplication.
Apart from above, I have clarified two sentences in doc-strings. The
updated patch is attached.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/2452#comment:11>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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