217: e to the pi Minus pi
|e to the pi Minus pi|
Title text: Also, I hear the 4th root of (9^2 + 19^2/22) is pi.
Computers use "floating point" numbers to store decimals. As noted in the comic, e^pi - pi is 19.999099979. However, Hat Guy's teammates' algorithms truncate to 3 decimal digits — giving a result of 19.999. Yet the programmers thought that 19.999 should come out to 20 unless they had errors in their algorithms (they did not; 19.999 would be the correct result). ACM is the Association for Computing Machinery; it sponsors the International Collegiate Programming Contest.
- In the title text, another mathematical coincidence is presented. The 4th root of (9^2 + 19^2/22) is 3.1415926525, which is extremely close to pi (≈3.1415926535).
- Cueball: Hey, check it out: e^pi-pi is 19.999099979. That's weird.
- Black Hat: Yeah. That's how I got kicked out of the ACM in college.
- Cueball: . . . what?
- Black Hat: During a competition, I told the programmers on our team that e^pi-pi was a standard test of floating-point handlers--it would come out to 20 unless they had rounding errors.
- Cueball: That's awful.
- Black Hat: Yeah, they dug through half their algorithms looking for the bug before they figured it out.
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