sympy
Peter Otten
__peter__ at web.de
Thu Mar 31 13:51:55 EDT 2016
Chris Angelico wrote:
> On Fri, Apr 1, 2016 at 1:55 AM, Peter Otten <__peter__ at web.de> wrote:
>> Hm, the two functions fmsympy() and fm() do not return the same value:
>>
>> $ python -i sympy_diff.py
>> 10000 evaluations with sympy : dt1 = 0.7178411483764648
>> 10000 evaluations without sympy: dt2 = 0.10177111625671387
>>>>> fm(42)
>> cos(42)
>>>>> fmsympy(42)
>> -0.399985314988351
>>
>
> Maybe not, but that's simply because one of them is completely
> evaluated. The cosine of 42 radians is indeed -0.4ish.
>
>>>> math.cos(42)
> -0.39998531498835127
My guess was that the OP fell into the trap that he himself carefully set up
with the star import, and accidentally used sympy.cos() where he wanted to
invoke math.cos().
The fix would actually increase the speed difference -- but first make it
right, then, maybe, fast.
Adding another storey to the tower of guesses, Robert Kern has probably
already provided the answer ;)
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