Yes, originally I used a 50 50 matrix. I've been looking for where I
recorded timings for various older machines. So if you find them first,
please send them along.
My memory, increasingly faulty, is that 50 50 took about 7 seconds on
the 360/50 (with a total of 256 Kbytes of RAM!), but that may have been
the time on the Philadelphia 360/75 much faster with a huge 1 Mbyte
RAM... This machine routinely supported 100+ users with 80 Kbyte workspaces.
Another bit of related trivia is that the Philadelphia 75 was a return
from NASA and the 60s space program. Also that Dick Lathwell had the
console panel from it for years, I think he donated it to a museum,
perhaps at Waterloo.
For comparison, I just did the 50 50 on my iPad and it takes 0.00956 seconds
Thanks for the reminders - your Hilbert one gives me the first chance to
report a crash of J on the iPad.
I tried it on my iMac
H=: %@>:@(+/~)@i.
6!:2 '%. H 100x'
80.0178
and then on the iPad - but after a few minutes, the app crashed, hard to
say what happened, not likely a memory issue since it takes considerably
less space than 500 500 ?@$ 1000
On 2012/05/11 20:07 , Roger Hui wrote:
> Somewhere I have recorded the times for the "JKT benchmark" on various
> machines over the years. But didn't you used to use 50 50 matrices?
> http://www.jsoftware.com/pipermail/programming/2007-December/009015.html
>
> Your report brings to mind two anecdotes concerning APL and matrix
> inverses. The first concerns Ken's doctoral thesis work, for which he
> solved some matrices for Leontief's input-output analysis. I've forgotten
> the size of the matrices involved; it was something like 50 by 50 and was
> on the Mark IV. Ken must have been an ace programmer. The Mark IV had a
> 200 word memory (?).
>
> The second anecdote is this:
> http://www.jsoftware.com/papers/APLQA.htm#Hilbert_matrix .
>
>
>
> On Fri, May 11, 2012 at 6:38 PM, Joey K Tuttle<[email protected]> wrote:
>
>> Wow! Is a response I've made several times about this new version of j.
>> Marvelous that such a powerful application is so compact.
>>
>> Since I couldn't resist, one of the first expressions I entered on my
>> iPhone 4 (not the faster 4s) was -
>>
>> 6!:2 '%. 500 500 ?@$ 1000'
>> 18.2
>>
>> Amazing!
>>
>> The graphs on the iPhone retina are beautiful. I need strong glasses to
>> hold it close enough to appreciate them and then the small font is OK too.
>> My iPad is a 2 and now I wish for the retina display there too (not to
>> mention the faster processor) - the inverse runs in 4.57 seconds on the
>> iPad 2, also amazing.
>>
>> - joey iPa...
>>
>> On May 11, 2012, at 8:27, John Baker<[email protected]> wrote:
>>
>>> First impressions - wow!
>>>
>>> I ran through the install process on plain old 3g connections - no
>> problems.
>>> The app comes up . I was able to step through the initial demos without
>>> problems. The standard J graphics
>>> look great on the iPhone 4.
>>>
>>> Is there anyway to change the size of the default session font? The
>>> current size is bit tiny for my old fart eyes.
>>>
>>> --
>>> John D. Baker
>>> [email protected]
>>>
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