[Numpy-discussion] why not zerodivision error?

Chao YUE chaoyuejoy at gmail.com
Sun May 20 08:19:45 EDT 2012


thanks for this information.

Chao

2012/5/20 eat <e.antero.tammi at gmail.com>

> Hi,
>
> On Sun, May 20, 2012 at 10:21 AM, Chao YUE <chaoyuejoy at gmail.com> wrote:
>
>> Dear all,
>>
>> could anybody give one sentence about this? why in the loop I didn't get
>> zerodivision error by when I explicitly do this, I get a zerodivision
>> error? thanks.
>>
>> In [7]: for i in np.arange(-10,10):
>>         print 1./i
>>    ...:
>> -0.1
>> -0.111111111111
>> -0.125
>> -0.142857142857
>> -0.166666666667
>> -0.2
>> -0.25
>> -0.333333333333
>> -0.5
>> -1.0
>> inf
>> 1.0
>> 0.5
>> 0.333333333333
>> 0.25
>> 0.2
>> 0.166666666667
>> 0.142857142857
>> 0.125
>> 0.111111111111
>>
>> In [8]: 1/0.
>>
>> ---------------------------------------------------------------------------
>> ZeroDivisionError                         Traceback (most recent call
>> last)
>> /mnt/f/data/DROUGTH/<ipython-input-8-7e0bf5b37da6> in <module>()
>> ----> 1 1/0.
>>
>> ZeroDivisionError: float division by zero
>>
>> In [9]: 1./0.
>>
>> ---------------------------------------------------------------------------
>> ZeroDivisionError                         Traceback (most recent call
>> last)
>> /mnt/f/data/DROUGTH/<ipython-input-9-3543596c47ff> in <module>()
>> ----> 1 1./0.
>>
>> ZeroDivisionError: float division by zero
>>
>> In [10]: 1./0
>>
>> ---------------------------------------------------------------------------
>> ZeroDivisionError                         Traceback (most recent call
>> last)
>> /mnt/f/data/DROUGTH/<ipython-input-10-523760448f92> in <module>()
>> ----> 1 1./0
>>
>> ZeroDivisionError: float division by zero
>
> You may like to read more on here
> http://docs.scipy.org/doc/numpy/reference/generated/numpy.seterr.html#numpy.seterr
>
> So, for your specific example:
> In []: a= arange(-10, 10)
> In []: 1./ a
> Out[]:
> array([-0.1       , -0.11111111, -0.125     , -0.14285714, -0.16666667,
>        -0.2       , -0.25      , -0.33333333, -0.5       , -1.        ,
>                inf,  1.        ,  0.5       ,  0.33333333,  0.25      ,
>         0.2       ,  0.16666667,  0.14285714,  0.125     ,  0.11111111])
> In []: seterr(divide= 'raise')
> In []: 1./ a
> ------------------------------------------------------------
> Traceback (most recent call last):
>   File "<ipython console>", line 1, in <module>
> FloatingPointError: divide by zero encountered in divide
>
>
> My 2 cents,
> -eat
>
>>
>>
>>
>> Chao
>>
>> --
>>
>> ***********************************************************************************
>> Chao YUE
>> Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
>> UMR 1572 CEA-CNRS-UVSQ
>> Batiment 712 - Pe 119
>> 91191 GIF Sur YVETTE Cedex
>> Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
>>
>> ************************************************************************************
>>
>>
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>> http://mail.scipy.org/mailman/listinfo/numpy-discussion
>>
>>
>
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>


-- 
***********************************************************************************
Chao YUE
Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL)
UMR 1572 CEA-CNRS-UVSQ
Batiment 712 - Pe 119
91191 GIF Sur YVETTE Cedex
Tel: (33) 01 69 08 29 02; Fax:01.69.08.77.16
************************************************************************************
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