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Labels: Type-Defect Priority-Medium
New issue 2128 by jagermeistermeister: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
Hi,
I'm new to sympy, so please forgive me if this is not a bug :-)
I am trying to integrat
Updates:
Status: Accepted
Labels: Integration Polynomial
Comment #1 on issue 2128 by asmeurer: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
In master, Integral(f, (x, -oo, oo)).evalf() hangs, Integral(f, (x, -oo,
oo)).d
Comment #2 on issue 2128 by jagermeistermeister: cannot integrate piecewise
function numerically
http://code.google.com/p/sympy/issues/detail?id=2128
Thank you for looking into it :)
Can anything be said about when the polys11 branch gets merged in? Perhaps
I could try/test the polys11 bra
Comment #3 on issue 2128 by jagermeistermeister: cannot integrate piecewise
function numerically
http://code.google.com/p/sympy/issues/detail?id=2128
I think I found the branch at
https://github.com/mattpap/sympy-polys/tree/polys11
I will test it :-)
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Comment #4 on issue 2128 by jagermeistermeister: cannot integrate piecewise
function numerically
http://code.google.com/p/sympy/issues/detail?id=2128
Oops, found an error already, where can I post a bug report regarding
Mateusz's polys11 branch? Should I just put it here?
Just in case:
a
Updates:
Cc: mattpap
Comment #5 on issue 2128 by asmeurer: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
I can confirm that that doesn't work, and it fails regardless of the ground
type. It also fails in the same way in master.
Comment #6 on issue 2128 by smichr: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
nsimplify the expression with flag rational=True and all works well in
master:
h[7] >>> integrate(nsimplify(f, rational=1), (x, -oo, oo)).n()
1.08063375
Updates:
Status: Started
Comment #7 on issue 2128 by mattpap: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
Regarding #3, I improved domain constructor to support real numbers better,
so now (in polys11) the example gives:
Not
Comment #8 on issue 2128 by asmeurer: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
Well, that error at least needs to be improved. I can hardly understand
what it is trying to say. And it uses old style "raise
NotImplementedError,
Comment #9 on issue 2128 by mattpap: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
I hardly understand it either, hoping that this is really a
NotImplementedError and not a wrong result passed to Piecewise by polys.
As to those except
Comment #10 on issue 2128 by jagermeistermeister: cannot integrate
piecewise function numerically
http://code.google.com/p/sympy/issues/detail?id=2128
Ok asmeurer, I will look at the code in (polys11) Piecewise._eval_interval
and post back here what I've found.
mattpap, great news that po
Comment #11 on issue 2128 by jagermeistermeister: cannot integrate
piecewise function numerically
http://code.google.com/p/sympy/issues/detail?id=2128
I found out why the error triggers.
In Piecewise._eval_interval there is this code:
if cond.args[0] == sym:
curr
Comment #12 on issue 2128 by asmeurer: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
I think .has() is what you want, i.e.,
In [12]: (x - z).has(y)
Out[12]: False
In [13]: (x - y).has(y)
Out[13]: True
You can also use the in operator:
Comment #13 on issue 2128 by mattpap: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
Actually, I'm not really sure what the difference between the two is.
has() is more general than __contains__(), e.g. it works with classes:
In [1]: (
Comment #14 on issue 2128 by jagermeistermeister: cannot integrate
piecewise function numerically
http://code.google.com/p/sympy/issues/detail?id=2128
Thanks asmeurer and mattpap, the in operator in combination with the
expression is what I'm looking for :)
Now I realise that I have been
Comment #15 on issue 2128 by asmeurer: cannot integrate piecewise function
numerically
http://code.google.com/p/sympy/issues/detail?id=2128
Maple can do it:
p:=piecewise(x - y < 0, 1, 0);
p := / 1 x - y < 0
{
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