Sergey,
Sorry, I misremembered: it was a limit, not a derivative. Here is an MWE:
from sympy import *
x = Symbol('x',positive=True)
z = Symbol('z')
def experiment1():
# Correctly returns oo
print limit(exp(x)**z,z,oo)
def experiment2():
# NotImplementedError: Result depends on the sign of sign(log(exp(x) +
1))
print limit((exp(x) + 1)**z,z,oo)
My best guess about what is happening is that in experiment1, log(exp(x))
is getting analytically simplified to x, but in experiment2 log(exp(x) + 1)
is not deduced to be greater than x?
Cheers,
Pat.
On Sat, Feb 8, 2014 at 4:30 PM, Sergey Kirpichev <[email protected]>wrote:
>
> On Sunday, February 9, 2014 12:24:56 AM UTC+4, Patrick O'Neill wrote:
>>
>> My problem arose when I tried to take a derivative of an expression, but
>> Sympy couldn't deduce the sign of the expression
>> log((N-1)+exp(beta*epsilon))/N) because of the problem I mentioned above.
>>
>
> What exactly you do?
>
> --
> You received this message because you are subscribed to the Google Groups
> "sympy" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to [email protected].
> To post to this group, send email to [email protected].
> Visit this group at http://groups.google.com/group/sympy.
> For more options, visit https://groups.google.com/groups/opt_out.
>
--
You received this message because you are subscribed to the Google Groups
"sympy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sympy.
For more options, visit https://groups.google.com/groups/opt_out.
