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Re: sympy

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From Peter Otten <__peter__@web.de>
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Subject Re: sympy
Date Thu, 31 Mar 2016 19:51:55 +0200
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Chris Angelico wrote:

> On Fri, Apr 1, 2016 at 1:55 AM, Peter Otten <__peter__@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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Thread

sympy Poul Riis <priisdk@gmail.com> - 2016-03-30 04:17 -0700
  Re: sympy Ben Finney <ben+python@benfinney.id.au> - 2016-03-30 22:29 +1100
  Re: sympy Ned Batchelder <ned@nedbatchelder.com> - 2016-03-30 04:39 -0700
  Re: sympy Steven D'Aprano <steve@pearwood.info> - 2016-03-30 23:56 +1100
    Re: sympy Poul Riis <priisdk@gmail.com> - 2016-03-30 08:23 -0700
      Re: sympy Robert Kern <robert.kern@gmail.com> - 2016-03-30 16:29 +0100
      Re: sympy Steven D'Aprano <steve@pearwood.info> - 2016-03-31 02:59 +1100
        Re: sympy Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-03-31 17:49 +1300
          Re: sympy Poul Riis <priisdk@gmail.com> - 2016-03-30 23:51 -0700
        Re: sympy Poul Riis <priisdk@gmail.com> - 2016-03-31 03:57 -0700
          Re: sympy Peter Otten <__peter__@web.de> - 2016-03-31 16:55 +0200
          Re: sympy Chris Angelico <rosuav@gmail.com> - 2016-04-01 04:05 +1100
          Re: sympy Peter Otten <__peter__@web.de> - 2016-03-31 19:51 +0200
          Re: sympy Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2016-03-31 19:59 +0100
  Re: sympy Poul Riis <priisdk@gmail.com> - 2016-03-31 14:33 -0700
    Re: sympy Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2016-03-31 23:26 +0100

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