[Jprogramming] j701 Speed Test

[Joey K Tuttle]

I agree with your point, but the "benchmark" has always included 
generating the matrix and that is typically a very small part of the 
time and should be relatively stable (although I suppose inverting the 
same "random" matrix over and over would remove some variation). Your 
suggestion of using a left argument for 6!:2 is the best way to reduce 
(or at lease smooth out) variability.

In repeating these expressions on my iPad, I discovered something I was 
never aware of before... I accidentally tacked a & onto the end of the 
expression - that has a very interesting (and actually useful) result. 
But because it is a pain to email selections from the iPad, these were 
done on an iMac i7 -

    100 (6!:2) '%. 50 50 ?@$ 1000'
0.00080055
    100 (6!:2) '%. 50 50 ?@$ 1000'&
0.000807989999999999967&
    0.1
0.1
    0.1&
0.100000000000000006&
    0j40 ": 0.1
0.1000000000000000055511151231257827021182

I never realized that tacking on the & displays the number which might 
be useful to see the actual floating point representation. May be about 
as silly as inverting random matrices, but also amusing...


On 2012/09/12 14:51 , Devon McCormick wrote:
> Part of the reason for the variability is that you're generating a new
> matrix each time and including the generation in your timing.
> Something like this should give a more stable result:
>
>     6!:2 '%.mat' [ mat=. 50 50?.@$1000
>
> Also, this form better allows you to run multiple timings to get a
> more stable number, e.g.:
>
>     (10) 6!:2 '%.mat'
>
> On Mon, Sep 10, 2012 at 3:29 PM, Robert Cyr <robert.cyr at gmail.com> wrote:
>> Results of the posted benchmark vary quie a bit: on this Nexus 7,
>>
>> 6!:2'%.50 50 ?.@$1000'
>> 0.043118
>>
>>    6!:2'%.50 50 ?.@$1000'
>> 0.033788
>>
>>    6!:2'%.50 50 ?.@$1000'
>> 0.030006
>>
>>    6!:2'%.50 50 ?.@$1000'
>> 0.034632
>>
>>    6!:2'%.50 50 ?.@$1000'
>> 0.023798
>>
>>    And with a larger sample,
>>
>>    6!:2'%.500 500 ?.@$1000'
>> 7.91767
>>
>>    6!:2'%.500 500 ?.@$1000'
>> 8.07115
>>
>>    6!:2'%.500 500 ?.@$1000'
>> 7.94837
>>
>> About twice the time of the iPad
>>   On Sep 9, 2012 6:53 AM, "bill lam" <bbill.lam at gmail.com> wrote:
>>
>>>  From google, iphone 4 uses cortex-a8 and that cpu uses vfp-lite which
>>> is 10 times slower than a regular vfp used in cortex-a9.
>>>
>>> Сбт, 08 Сен 2012, Joey K Tuttle писал(а):
>>>> That's a nice speedup! It will be interesting to try the iPhone 5.
>>>>
>>>> I'm curious if anyone has a timing from a generation 3 iPad, it may
>>>> well be faster than my iPad 2.
>>>>
>>>> On 2012/09/08 06:30 , J. Patrick Harrington wrote:
>>>>>
>>>>> The iPhone 4S is faster: 5.6 sec
>>>>>
>>>>> On Fri, 7 Sep 2012, Joey K Tuttle wrote:
>>>>>> iPhone 4   -  18.2 seconds
>>>>>> iPad 2     -   4.6 seconds
>>>>>>
>>>>>> On 2012/09/07 19:48 , bill lam wrote:
>>>>>>> I am curious to know what are the timings for iphone and ipad.
>>>>>>>
>>>>>>> It is around 6 to 11 seconds on android depending on CPU.
>>>>>>>
>>>>>>> Срд, 05 Сен 2012, Paul Jackson писал(а):
>>>>>>>> Some time ago, you and Roger were talking about timings on
>>>>>>>>      %. 500 500 ?@$ 1000
>>>>>>>>
>>>>>>>> I believe Roger said he had timings from the IPSA days.  He also
>>>>>>>> said the
>>>>>>>> matix was considerably smaller.  Did you ever get those early machine
>>>>>>>> timings?
>>>>>>>>
>>>>>>>> Paul