217: e to the pi Minus pi

2013-01-03T16:49:44Z

71.172.44.129: /* Explanation */

{{comic
| number = 217
| date = January 31, 2007
| title = e to the pi Minus pi
| image = e_to_the_pi_minus_pi.png
| imagesize =
| titletext = Also, I hear the 4th root of (9^2 + 19^2/22) is pi.
}}

==Explanation==
"e" is a mathematical constant that is about equal to 2.71828182846. π is about equal to 3.14159265359.

Computers use "floating point" numbers to store decimals. As noted in the comic, e^π - π 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).

==Transcript==
: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.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Black Hat]]
[[Category:Math]]

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217: e to the pi Minus pi