Help with recognizing e

[נדב שוייגר‎]

Hi, I'm creating a derivative tool as an exercise using SymPy.

I get this following problem when using it:

The tool is based on receiving textual user input and assuming deriving in respect to 'x'.

In order to do so, i set x as a symbol and pass it as the second parameter to diff(). 

When differentiating "e**x" I get: "e**x*log(e)". This answer, while correct, bothers me because I'd like SymPy to know that log(e) == 1.

Any help?

[Aaron Meurer]

The SymPy name for exp(1) is E.

If you are using sympify() or parse_expr() you can map e to E using locals:

In [38]: sympify('log(e)', locals={'e': E})
Out[38]: 1

That's basically equivalent to running

e = E

before the given expression.

Aaron Meurer

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