Python fails on math

Grant Edwards invalid at invalid.invalid
Wed Feb 23 16:24:49 CET 2011


On 2011-02-23, Terry Reedy <tjreedy at udel.edu> wrote:
> On 2/22/2011 2:42 PM, Grant Edwards wrote:
>
>> Except that Python (and computer languages in general) don't deal with
>> real numbers.  They deal with floating point numbers, which aren't the
>> same thing.  [In case anybody is still fuzzy about that.]
>
> In particular, floats are a fixed finite set of rationals with adjusted 
> definitions of the arithmetic operators. The adjustment is necessary 
> because the 'proper' answer to an operation may not be one of the 
> allowed answers. In other words, f1 float-op f2 may not be the same as 
> f1 rat-op f2, and hence float-ops do not always obey the rules of 
> rational (or real) operations.

On some (increasingly rare) systems they don't always obey the rules
of base-two float-opts either, but that's a whole different can of
worms.

-- 
Grant Edwards               grant.b.edwards        Yow! I want a VEGETARIAN
                                  at               BURRITO to go ... with
                              gmail.com            EXTRA MSG!!



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