symbolic derivation of a larger function

Question

I want to take the derivative of the following function y=(np.log(x))/(1+x), if I am using sympy, it gives me the following error

    from sympy import *
    y1=Derivative((np.log(x))/(1+x), x)
    print y1

sequence too large; cannot be greater than 32

Is that all of your code? Should you not introduce some symbolic variables to sympy (instead on passing undefined python variables like ```x```)? — sascha, Jan 13 '17 at 03:25
@Sanjeev Although it may seem inconvenient, try to [avoid `from ... import *`](http://stackoverflow.com/questions/2386714/why-is-import-bad). — MB-F, Jan 13 '17 at 08:05

score 1 · Accepted Answer · answered Jan 13 '17 at 04:32

1

Do it like this:

>>> from sympy import *
>>> var('x')
x
>>> y1 = diff(log(x)/(1+x))
>>> y1
-log(x)/(x + 1)**2 + 1/(x*(x + 1))

As Sanjeev mentioned in a comment you need to define variables in one way or another.
np.log in your code would be a function that accepts a numerical value and returns a numerical value; sympy needs to see a function names that it knows in formal terms, such as log
In this context, you need to use sympy's diff function, rather than Derivative.

answered Jan 13 '17 at 04:32

Bill Bell

Thanks Bell...Today I went through the complete documentation of sympy from the start and found this thing....thanks a lot!!! and thanks for explaining the np.log thing – Sanjeev Jan 13 '17 at 16:13
Sanjeev, you're most welcome. I hope you enjoy using sympy as much as I do. – Bill Bell Jan 13 '17 at 16:15

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