"Russ" <[EMAIL PROTECTED]> writes:
> Ben Cartwright wrote:
>> Russ wrote:
>
>> > Does "pow(x,2)" simply square x, or does it first compute logarithms
>> > (as would be necessary if the exponent were not an integer)?
>>
>>
>> The former, using binary exponentiation (quite fast), assuming x is an
>>
"Russ" <[EMAIL PROTECTED]> writes:
> I just did a little time test (which I should have done *before* my
> original post!), and 2.0**2 seems to be about twice as fast as
> pow(2.0,2). That seems consistent with your claim above...>
> I just did another little time test comparing 2.0**0.5 with sqrt
"Mike Ressler" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> I have a counterexample. In the original timeit example, 111**111 was
> used. When I run that
>
timeit.Timer("pow(111,111)").timeit()
> 10.968398094177246
timeit.Timer("111**111").timeit()
> 10.04007887840271
>
Mike Ressler wrote:
> >>> timeit.Timer("pow(111,111)").timeit()
> 10.968398094177246
> >>> timeit.Timer("111**111").timeit()
> 10.04007887840271
> >>> timeit.Timer("111.**111.").timeit()
> 0.36576294898986816
>
> The pow and ** on integers take 10 seconds, but the float ** takes only
> 0.36 seconds
On Wed, 2006-03-15 at 18:46 -0800, Ben Cartwright wrote:
> Anyway, if you want to see the int vs. float issue in action, try this:
>
> >>> from timeit import Timer
> >>> Timer('2**2').timeit()
> 0.12681011582321844
> >>> Timer('2.0**2.0').timeit()
> 0.6011743438121
> >>> Timer('2.
Russ wrote:
> Ben Cartwright wrote:
> > Russ wrote:
>
> > > Does "pow(x,2)" simply square x, or does it first compute logarithms
> > > (as would be necessary if the exponent were not an integer)?
> >
> >
> > The former, using binary exponentiation (quite fast), assuming x is an
> > int or long.
> >
Ben Cartwright wrote:
> Russ wrote:
> > Does "pow(x,2)" simply square x, or does it first compute logarithms
> > (as would be necessary if the exponent were not an integer)?
>
>
> The former, using binary exponentiation (quite fast), assuming x is an
> int or long.
>
> If x is a float, Python coer
Russ wrote:
> I have a couple of questions for the number crunchers out there:
Sure, but the answers depend on the underlying Python implementation.
And if we're talking CPython, they also depend on the underlying C
implementation of libm (i.e., math.h).
> Does "pow(x,2)" simply square x, or do
Schüle Daniel <[EMAIL PROTECTED]> writes:
> >>> timeit.Timer("111**0.3").timeit()
> 2.3824679851531982
> >>> timeit.Timer("pow(111,0.3)").timeit()
> 4.2945041656494141
>
> interesting result
> seems that ** computates faster
Maybe "111**0.3" parses faster than pow(111,0.3), if timeit uses eval.
I not shure which algorithm,but I am assumeing that all Python does,is
to call the underlying C pow() function.
Sam
--
http://mail.python.org/mailman/listinfo/python-list
Russ wrote:
> I have a couple of questions for the number crunchers out there:
>
> Does "pow(x,2)" simply square x, or does it first compute logarithms
> (as would be necessary if the exponent were not an integer)?
>
> Does "x**0.5" use the same algorithm as "sqrt(x)", or does it use some
> other
I have a couple of questions for the number crunchers out there:
Does "pow(x,2)" simply square x, or does it first compute logarithms
(as would be necessary if the exponent were not an integer)?
Does "x**0.5" use the same algorithm as "sqrt(x)", or does it use some
other (perhaps less efficient)
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