Emma Haruka Iwao sets a Guinness World Record for the most accurate value of Pi: NPR

Emma Haruka Iwao grew fascinated by the pi. Now she has calculated more than $ 31 trillion.

Iwao set Thursday the Guinness world's most recent record for pi's most accurate value. The Google employee and his team calculated 31,415,926,535,897 figures – crushing a 2016 record by billions of numbers.

And all this brings us back to the curiosity of his childhood for the mathematical constant – the relationship between the circumference of a circle and its diameter.

"I loved computers when I was a kid," she told NPR Here Now. "And I learned that some people use computers to calculate millions and billions of pi digits. It seemed so fascinating to me."

Pi was estimated for the first time thousands of years ago and by the middle of the 20th century mathematicians had calculated about 1,000 figures, with the help of a calculator. gears. But the birth of the digital computer in the 20th century had the effect of overloading pi's estimation efforts more accurately. In 2009, Daisuke Takahashi of the University of Tsukuba was calculating about 2,600 billion pound figures with a supercomputer.

Iwao knew Takahashi when she was a child, she said, because he held the world record at the time, alongside the Japanese mathematician Yasumasa Kanada. Iwao was inspired by their work and she was going to study at university with Takahashi. When she later told him about her own attempt to calculate pi figures, "he shared his tips and some technical strategies," she said in a Google blog post.

But when Iwao broke the record herself, she did not use a supercomputer. Instead, she used y-cruncher, an application that everyone can download and run on 25 Google Cloud virtual machines.

Even with Google's infrastructure on its side, determining billions of dollars was not a simple task. According to Google, the calculation took about four months and about 170 terabytes of data, or "roughly the equivalent of the amount of data from the entire library of Congress printed collections".

Is his result useful? Not in a practical sense, admits Iwao. "For engineering and science applications," she says, "you probably will not need more than 100 digits." NASA, for example, only needs to use rounded pi to the 15th decimal to send a spacecraft to the moon.

But, she says, it will be helpful for anyone studying pi's features to better understand numbers through statistical analysis. And for her and her colleagues in her Tokyo office, she adds, it was worth celebrating with "a real pie".

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