Calculating Pi (3.14) on the Raspberry Pi 2-- How Fast Is It?

RE: Calculating Pi (3.14) on the Raspberry Pi 2-- How Fast Is It?

Former Member — Tue, 31 Mar 2015 00:16:37 GMT

hi Cabe, Clem, et al

Well I got my Raspberry PI 2 today, and finally got it on the network with wipi...

Here's my times using Python3 and pdeclib.py pilib.py and piagm2():

With dscale(10010) :

raspberry PI b+: 1m58s

raspberry PI 2: 1m12s

... and that's for 10,000+ digits !

Blows your doors off, ey?

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RE: Calculating Pi (3.14) on the Raspberry Pi 2-- How Fast Is It?

Former Member — Sat, 28 Mar 2015 23:37:58 GMT

If you are going to dream, wish for (at least) double the RAM. Insufficient RAM is the largest issue in any SoC. E.g. if we had more RAM, we could set up /tmp and /run as tmpfs in /etc/fstab. That would cut down a great deal on actual disk I/O.

In a couple of years, I'll bet that the Pi version 3 or 4 with the same footprint will have 64-bit quad cores in a little.Big package. RAM will be faster and probably at least 4GB in capacity. I'm going to buy one for my granddaughter (she'll be 4-5 years old then).

RE: Calculating Pi (3.14) on the Raspberry Pi 2-- How Fast Is It?

Former Member — Wed, 25 Mar 2015 07:57:44 GMT

hi Cabe, I am surprised that you did not use Python on the PI to calculate PI! At any rate you might try this in BC

16 * a(1/5) - 4 * a(1/239)

That formula will converge much faster... try it on all three models and report back...

Alternately you could use Python3 and the new Decimal module (built-in); makes BC look like a brick. And fast... oh

my goodness. I wrote a library for it that you can get at PYPi called pdeclib. If you have PIP installed you can install it

with PIP. Alternately you can get pdeclib from PythonDecimalLibrary on Google Code. Or, I'll send you a copy.

Anyway, there is a routine (AGM) in pdeclib (comes with pilib) called piagm2(). This will compute PI to arbitrary precision

and 'fast' does not even begin to define it. It screams. You need to use Python3 to get the fast version of the Decimal

library, but, my pdeclib will work (very fast) regardless (I run it on python 2.7.3 on my droid phone!)

I have a Raspberry PI 2 on order now... let you know how it goes/

Kind regards,

marcus

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RE: Calculating Pi (3.14) on the Raspberry Pi 2-- How Fast Is It?

gulfboy — Mon, 23 Mar 2015 18:37:41 GMT

I tried running the Octane 2.0 test on my Pi 2 and got much lower results (example: Octane Score = 333 vs 20377 from your test) Which browser did you use?

RE: Calculating Pi (3.14) on the Raspberry Pi 2-- How Fast Is It?

Former Member — Tue, 17 Mar 2015 22:08:53 GMT

The statement, "Pi 2 is getting results close to desktop processors", is a bit over the top. I ran `time echo "scale=2015; 4*a(1)" | bc -l` on an ASROCK H67M-ITX/HT Mini-ITX motherboard with an Intel i3-2100T 2.1 MHz CPU which is fairly modest by today's desktop standards. The resulting timings were as follows:

real 0m2.652s

user 0m2.652s

sys 0m0.001s

That puts the ASROCK motherboard at nearly 6 times as fast as a Pi 2 which I do plan to buy but certainly not for its computation ability.

RE: Calculating Pi (3.14) on the Raspberry Pi 2-- How Fast Is It?

Former Member — Mon, 16 Mar 2015 10:21:55 GMT

I noticed that your calculated improvement running "at 32 Ops/Word" shows 83% which seemed wrong so I did the sum and it gave me 827%.

RE: Calculating Pi (3.14) on the Raspberry Pi 2-- How Fast Is It?

cstanton — Wed, 11 Mar 2015 15:05:30 GMT

I've found that the Pi 2 happily overclocked to 1Ghz (via raspi-config) have you considered doing this and checking how fast it'll calculate it then, to see if it makes much difference?