Learning Python : >>> import math doesn't work ?
dpsanders at gmail.com
Mon Nov 19 05:21:03 CET 2007
On Nov 18, 8:48 pm, pdlem... at earthlink.net wrote:
> Have carefully installed Python 2.5.1 under XP in dir E:\python25 .
> ran set path = %path% ; E:\python25
> Python interactive mode works fine for simple arithmetic .
> Then tried >>> import math
> >>> x = sqrt(100)
> Get error Name error : name 'sqrt' is not defined
> Same thing with sin(x) .
> I'm unable to find "math" , "sqrt" , or "sin" anywhere in lib , Libs
> or include directories .
> The Tutorial does not clear this up .
> Please help. Thanks Dave pdlem... at earthlink.net
I believe that should be:
x = math.sqrt(100)
'import math' makes available the functions in the math module, but
they are still inside the math namespace, so still require 'math.'
If you will be using sqrt a lot, you can create a copy of the function
in the local namespace using
sqrt = math.sqrt
x = sqrt(100)
[In principle, you can give it any name you want, but of course it is
sensible to use a name that makes sense.
E.g. if you were a Spanish speaker, you could say instead
raiz = math.sqrt
x = raiz(100)
For more details about how 'import'ing works, check out the Python
Hope that helps.
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