[Python-Dev] C Decimal - is there any interest?

[Mateusz Rukowicz]

Mark Dickinson wrote:

>On 10/16/07, Fredrik Johansson <fredrik.johansson at gmail.com> wrote:
>  
>
>>A more radical proposal would be to change Python's long type to use a
>>radix-10**n representation (Python 3000 or beyond?).
>>    
>>
>
>Mightn't this produce significant (constant factor) slowdowns for long
>performance?  As I understand it, the main problem with a base 10**n
>representation is that, for example, extracting the high and low limbs
>of the 2-limb result of a 1-limb by 1-limb multiplication requires a
>division, whereas for integers stored in binary that division can be
>replaced by bit operations.
>
>  
>
>>An implementation
>>of decimal floating-point arithmetic on top of it, whether written in
>>C or pure Python (if some utility C functions such as for counting the
>>number of digits an integer were available), would be both
>>light-weight and efficient at high precision.
>>    
>>
>
>Agreed.  But it might be hard to sell a more efficient decimal module
>at the expense of slower integer arithmetic in core Python.
>
>  
>
My 2 cents -- integer division and modulo (needed for 10**n radix) is so 
slow, that in some extremal cases algorithm may slow down by a factor of 
4-5, so I guess it's not an option. Not to mention binary logical 
operations.