Hi,
I have to admit I am new to sympy and deeply impressed what sympy can do.
When experimenting with integrating a Gaussian distribution, I got a
backtrace. Just wondering if I did something wrong.
My experiment:
import sympy as sp
> sp.init_printing()
>
> # Define Gaussian distribution
> sigma=sp.Symbol('sigma', positive=True)
> mu=sp.Symbol('mu',domain=sp.S.Reals)
> x=sp.Symbol('x')
> f=1/sp.sqrt(2*sp.pi*sigma**2)*sp.exp(-(x-mu)**2/(2*sigma**2))
>
> # Integrate
> g=sp.integrate(f,x)
> h=g-g.subs(x,-sp.oo)
> h
>
> # Simplify full Intervall - 1 is expected
> sp.simplify(h.subs(x,sp.oo))
>
> The output I got
>
rd@h370:~/tmp.nobackup$ python3 sympy-test.py
Traceback (most recent call last):
File "sympy-test.py", line 16, in <module>
sp.simplify(h.subs(x,sp.oo))
File "/usr/lib/python3/dist-packages/sympy/simplify/simplify.py", line 566
, in simplify
expr1 = shorter(_e, _mexpand(_e).cancel()) # issue 6829
File "/usr/lib/python3/dist-packages/sympy/core/expr.py", line 3245, in
cancel
return cancel(self, *gens, **args)
File "/usr/lib/python3/dist-packages/sympy/polys/polytools.py", line 6583,
in cancel
f = factor_terms(f, radical=True)
File "/usr/lib/python3/dist-packages/sympy/core/exprtools.py", line 1202,
in factor_terms
return do(expr)
File "/usr/lib/python3/dist-packages/sympy/core/exprtools.py", line 1177,
in do
list_args = [do(a) for a in Add.make_args(p)]
File "/usr/lib/python3/dist-packages/sympy/core/exprtools.py", line 1177,
in <listcomp>
list_args = [do(a) for a in Add.make_args(p)]
File "/usr/lib/python3/dist-packages/sympy/core/exprtools.py", line 1198,
in do
*[do(a) for a in p.args])
File "/usr/lib/python3/dist-packages/sympy/core/exprtools.py", line 1198,
in <listcomp>
*[do(a) for a in p.args])
File "/usr/lib/python3/dist-packages/sympy/core/exprtools.py", line 1167,
in do
newargs = tuple([do(i) for i in args])
File "/usr/lib/python3/dist-packages/sympy/core/exprtools.py", line 1167,
in <listcomp>
newargs = tuple([do(i) for i in args])
File "/usr/lib/python3/dist-packages/sympy/core/exprtools.py", line 1199,
in do
rv = _keep_coeff(cont, p, clear=clear, sign=sign)
File "/usr/lib/python3/dist-packages/sympy/core/mul.py", line 1793, in
_keep_coeff
if r == int(r):
File "/usr/lib/python3/dist-packages/sympy/core/expr.py", line 229, in
__int__
raise TypeError("can't convert %s to int" % r)
TypeError: can't convert -oo to int
rd@h370:~/tmp.nobackup$
sp.simplify(h.subs(x,sp.oo).subs(mu,0))
works well and returns 1 as expected.
Do I need to restrict mu further or did I hit a sympy issue? Or something
completely different?
Any feedback is welcome.
Thanks
Rainer
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