*Golden Ratio*is one of the oldest and most visible irrational numbers known to humanity.

*Pi*is perhaps more famous, but the

*Golden Ratio*is found in more of our art, architecture, and culture throughout human history.

*Golden Ratio*as sort of "

*Pi in 1 dimension*". Whereas

*Pi*is the ratio of a circle's circumference to its diameter, the

*Golden Ratio*is the ratio of a whole to one of its parts, when the ratio of that part to the remainder is equal.

*Golden Ratio*in the architecture of antiquity, from the Egyptians to the Greeks to the Romans, right up to the Renaissance and even modern times.

*Golden Ratio*can be observed as the base and the hypotenuse of a basic triangular cross section like so:

*Golden Ratio*...

*Golden Ratio*.

*Golden Ratio*throughout his works. I'm told that his

*Vitruvian Man*displays the

*Golden Ratio*...

*Golden Ratio*is approximately ~1.6 (and change).

*Golden Ratio*is in fact an irrational number and can be calculated to much greater precision through several different representations, including:

*y-cruncher*, which as been used to calculate most of the famous constants to world record precision.

*(Sorry free software readers of this blog -- y-cruncher is not open source code...)*

*y-cruncher*a few weeks ago when I was working on the mprime post, demonstrating how you can easily put any workload into a Docker container and then produce both Juju Charms and Ubuntu Snaps that package easily. While I opted to use mprime in that post, I saved

*y-cruncher*for this one :-)

*y-cruncher*.

*Golden Ratio*record (1 trillion digits, by Alexander Yee on his gaming PC in 2010). I say "affordable", in that I could have cracked that record "2x faster" with a d2.4xlarge or d2.8xlarge, however, I would have paid much more (4x) for the total instance hours. This was purely an economic decision :-)

- 8x Intel Xeon CPUs (E5-2676 v3 @ 2.4GHz)
- 60GB of Memory
- 6x 2TB HDDs

*mdadm*, and formatted it with xfs (which performed better than ext4 or btrfs in my cursory tests).

$ sudo mdadm --create --verbose /dev/md0 --level=stripe --raid-devices=6 /dev/xvd? $ sudo mkfs.xfs /dev/md0 $ df -h /mnt /dev/md0 11T 34M 11T 1% /mnt

$ sudo hdparm -tT /dev/md0 Timing cached reads: 21126 MB in 2.00 seconds = 10576.60 MB/sec Timing buffered disk reads: 1784 MB in 3.00 seconds = 593.88 MB/sec

Program Version: 0.6.8 Build 9461 (Linux - x64 AVX2 ~ Airi) Constant: Golden Ratio Algorithm: Newton's Method Decimal Digits: 2,000,000,000,000 Hexadecimal Digits: 1,660,964,047,444 Threading Mode: Thread Spawn (1 Thread/Task) ? / 8 Computation Mode: Swap Mode Working Memory: 61,342,174,048 bytes ( 57.1 GiB ) Logical Disk Usage: 8,851,913,469,608 bytes ( 8.05 TiB )

*Byobu*was very handy here, being able to track in the bottom status bar my CPU load, memory usage, disk usage, and disk I/O, as well as connecting and disconnecting from the running session multiple times over the 4 days of running.

Start Date: Thu Jul 16 03:54:11 2015 End Date: Sun Jul 19 11:14:52 2015 Computation Time: 221548.583 seconds Total Time: 285640.965 seconds CPU Utilization: 315.469 % Multi-core Efficiency: 39.434 % Last Digits: 5027026274 0209627284 1999836114 2950866539 8538613661 : 1,999,999,999,950 2578388470 9290671113 7339871816 2353911433 7831736127 : 2,000,000,000,000

*Golden Ratio*record.

Now, let's talk about the economics here, which I think are the most interesting part of this post.

Look at the above chart of records, which are published on the

*y-cruncher*page, the vast majority of those have been calculated on physical PCs -- most of them seem to be gaming PCs running Windows.

What's different about my approach is that I used Linux in the Cloud -- specifically Ubuntu in AWS. I paid hourly (actually, my employer, Canonical, reimbursed me for that expense, thanks!) It took right at 160 hours to run the initial calculation (79 hours) as well as the verification calculation (81 hours), at the current rate of $1.38/hour for a d2.2xlarge, which is a grand total of $220!

$220 is a small fraction of the cost of 6x 2TB disks, 60 GB of memory, or 8 Xeon cores, not to mention the electricity and cooling required to run a system of this size (~750W) for 160 hours.

If we say the first first trillion digits were already known from the previous record, that comes out to approximately 4.5 billion record-digits per dollar, and 12.5 billion record-digits per hour!

Hopefully you find this as fascinating as I!

Cheers,

:-Dustin