On International Pi Day (3/14, the first three digits of π), scientists worldwide celebrate the number through competitions, presentations and… of course, eating pie!

Grab yourself a slice of pie, because an epic π record was set in Switzerland.

Using a high-performance computer, a team of Swiss researchers have calculated a new most accurate value of pi.

The record-breaking value counts 62,831,853,071,796 digits, as confirmed by project leader Thomas Keller and his team on 19 August 2021, adding 12.8 billion new digits to pi. 

The attempt was led by DAViS (Centre for Data Analytics, Visualisation and Simulation), a regional competence centre for research, industry and education that operates within the University of Applied Science of the Grisnos located in Chur, Switzerland.

The calculation on the DAViS computer shortly after the beginning of the attempt

As stated in their project summary, DAViS' machine used the operating system Ubuntu 20.04 on the computation unit. 

For the calculation, like for all the previous most accurate value of pi records, it used the software y-cruncher (developed by Alexander J. Yee).

The hardware assembly and the installation of the operating system took about three days, but that was only the beginning.

"It took me about one month to tune different parameters of the operating system and y-cruncher (the pi calculation program)," said Keller.

Overall the whole computation took 108 days and 9 hours to complete. 

Project leader Thomas Keller

The attempt presented a series of challenges, especially considering the scope of the calculation.

"The main challenge is the enormous amount of data this calculation produces (about 310 TB to store intermediate results) and to keep the computation running over several months without data loss," - Thomas Keller

"I did a lot of test runs, calculating pi to lower numbers of digits, to get a firm idea on what to expect during a record attempt."

Further issues were then encountered with the backup system.

"One problem we were facing: our new backup system was delayed, and we had to improvise to backup the intermediate results of the pi calculation." 

Shutterstock pi day cherry pie

What is pi, and why is it calculated?

Pi is a mathematic constant defined as: "the ratio of the circumference of a circle to its diameter". 

It usually gets approximated to 3.14159, but scientists have calculated billions of digits.

For most of us, pi is that series of digits that we all used in school — though, let's be honest, we never really understood why

In fact, π has represented a fascinating riddle for mathematics through the eras and keeps being used in geometry, mathematics, and technology.

Today, we keep adding digits to pi for two reasons: to avoid any rounding error, and use the computation as a benchmark for high-performance computers.

"The 62.8 trillion digits of pi are only a side effect of testing and benchmarking our new computing infrastructure," explained Keller. 

"Pi has been known for centuries to a precision of several hundred digits. Even in the most precise calculations in science and engineering, a few dozen digits are enough."

 The algorithm to calculate Pi, established in 1988 by the Chudnovsky brothers

Although there is no practical reason to calculate dozens of billions of digits, setting a new record for the most accurate value of pi meant to:

  •  Prove that there could be an efficient calculation to 62.8 trillion decimal places with limited hardware, budget and personnel.
  •  Test the benchmark for the computer used for the attempt.
  •  Test DAViS’ ability to continuously run a calculation (and a record attempt) for a long period of time. 

How was the DAViS computer able to calculate the digits?

"The main reason, we believe, boils down to how fast data can be transferred between RAM (Memory) and hard disk drives."

"Due to financial constraints, we opted for relatively slow, but reliable hard disk drives. To somewhat offset this speed disadvantage, we connected our disks over a fast data bus (wiring/cables) to the memory and CPU."

 The storage system of the DAViS machine. The yellow area represents the y-cruncher and operating system, while the red area is the separate enclosure with the Hard Disk Drives (HDDs)

Energy: an environmental note

In 2022, we are all facing a climate crisis that made us all more conscious of the amount of power we consume. 

So one might wonder: how much energy was used by the DAViS computer for this record? 

The answer is: less than you may think! 

"The computing unit with CPUs, memory and SSDs consumes approx. 300 watts of power. The JBOD with 38 HDDs requires approx. 430 watts."

Even considering all those different processes, the estimated power needed for this calculation amounted to around 1,700 watts.

Sounds like a lot? 

You may be surprised to know that's approximately the same as a conventional hairdryer.

Happy Pi Day, everyone!