Looks interesting! Does anyone know a practical application where something like this would help?
It's another way to help verify super long calculations of pi are correct, and in turn I guess one basic "practical application" of calculating pi to many digits is as part of the suite for verifying new hardware. How do you know that fancy fresh new silicon is actually crunching the numbers correctly, not producing garbage in some subtle way at enough significant digits? While there are lots and lots of checks used to avoid a repeat of hardware bugs of days past (like the forever infamous Pentium FDIV), one simple sanity check/stress test is calculating out numbers like pi a bunch of different ways to huge numbers of digits and making sure the result is always correct. If it's not there's clearly a problem somewhere.