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| {{comic | | {{comic |
| | number = 217 | | | number = 217 |
− | | date = January 31, 2007 | + | | date = |
| | title = e to the pi Minus pi | | | title = e to the pi Minus pi |
| | image = e_to_the_pi_minus_pi.png | | | image = e_to_the_pi_minus_pi.png |
| + | | imagesize = |
| | titletext = Also, I hear the 4th root of (9^2 + 19^2/22) is pi. | | | titletext = Also, I hear the 4th root of (9^2 + 19^2/22) is pi. |
| }} | | }} |
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| ==Explanation== | | ==Explanation== |
− | {{w|e (number)|e}} is a {{w|mathematical constant}} roughly equal to 2.71828182846. {{w|pi|π}} is another, roughly equal to 3.14159265359.
| + | 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. |
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− | The first panel discusses {{w|Gelfond's constant|e<sup>π</sup>}} − π, which is around 19.999099979 — very close to 20. [[Black Hat]] explains how he tricked a programming team into believing that e<sup>π</sup> − π really equals 20 — instead of just being weirdly close — thus that any noticeable deviation from 20 results from errors in the code. This made them waste a lot of time trying to find a nonexistent bug until they realized that Black Hat was lying (clearly they had not known him for very long, and clearly they weren't very knowledgeable in mathematics).
| + | :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). |
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− | {{w|Floating point}} numbers are how computers store non-integer real numbers as decimals — or rather, in most cases, approximate them: infinite amounts of data would be required to represent most numbers in decimal form (exceptions are {{w|integers}} and {{w|terminating decimal}}s). The "floating-point handlers" would be the code performing the e<sup>π</sup> − π calculation.
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− | ACM is the {{w|Association for Computing Machinery}}, which at the time of writing sponsored the {{w|ACM International Collegiate Programming Contest|International Collegiate Programming Contest}}. It is likely that it was this competition, in which Black Hat wasted his team's time, for which he got kicked out.
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− | The title text pokes fun at another coincidence: ∜(9² + 19²/22) ≈ 3.1415926525, equating close to π (deviating only in the 9th decimal place). The humor comes from the fact that π is {{w|transcendental number|transcendental}}. Transcendental numbers are numbers that cannot be expressed through basic arithmetic with integers; one cannot end up with the exact value for any transcendental number (including π) by adding, subtracting, multiplying, dividing, exponentiating, and/or taking the nth root of any rational number, meaning the title text cannot possibly be true. This coincidence was discovered by Ramanujan while {{w|squaring the circle}} in 1914. | |
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− | A much later comic, [[1047: Approximations]], puts forth quite a few more mathematical coincidences.
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| ==Transcript== | | ==Transcript== |
− | :Cueball: Hey, check it out: e<sup>π</sup> − π is 19.999099979. That's weird. | + | :Person: 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. | + | :Hat Guy: Yeah. That's how I got kicked out of the ACM in college. |
− | :Cueball: ...what? | + | :Person: . . . what? |
− | :Black Hat: During a competition, I told the programmers on our team that e<sup>π</sup> − π was a standard test of floating-point handlers -- it would come out to 20 unless they had rounding errors. | + | :Hat Guy: 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. | + | :Person: That's awful. |
− | :Black Hat: Yeah, they dug through half their algorithms looking for the bug before they figured it out. | + | :Hat Guy: Yeah, they dug through half their algorithms looking for the bug before they figured it out. |
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− | ==Trivia==
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− | * e<sup>π</sup> − π is an {{w|irrational number}}. It was proven by {{w|Yuri Valentinovich Nesterenko}} in the late 20th century.
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− | * At the time when this comic was published, the mysterious almost-equation e<sup>π</sup> − π ≈ 20 was believed to be a {{w|mathematical coincidence}}, or a numerical relationship that "just happens" with no satisfactory explanation. In September 2023, an explanation was found based on the {{w|Theta_function#Jacobi_identities|Jacobi identities}}.
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− | {{comic discussion}} | + | {{comic discussion}} |
− | [[Category:Comics featuring Cueball]]
| + | <!-- Include any categories below this line--> |
− | [[Category:Comics featuring Black Hat]]
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− | [[Category:Math]]
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− | [[Category:Programming]]
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