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| bio | website | |
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| location | ||
| age | ||
| visits | member for | 2 years, 4 months |
| seen | 3 hours ago | |
| stats | profile views | 160 |
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May 16 |
comment |
Why is 0 false? This argument just about works for abusing bitwise | as a Boolean operator but it breaks down for & and ^ because of the existence of distinct non-zero values. |
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May 14 |
comment |
Single codebase for client and server with Node.js @hippietrail, en.wikipedia.org/wiki/WAR_file_format_(Sun) |
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May 14 |
answered | Single codebase for client and server with Node.js |
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May 4 |
comment |
Is there any situation when there's no alternative to instanceof? There's a variant on the second approach which can be used in e.g. Java: try an explicit cast and be ready to catch the ClassCastException. It's probably open for debate whether this is really just hiding an instanceof check behind syntactic sugar. |
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May 1 |
awarded | Nice Answer |
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Apr 26 |
comment |
Why does Donald Knuth write TAOCP using assembly language? Knuth implemented an ALGOL compiler in 1960, and ALGOL was intended to be suitable for publishing algorithms, so I don't think this really answers the question. |
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Apr 25 |
awarded | Custodian |
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Apr 17 |
comment |
Does any well-known license require to make modifications available when only derived *output* is published? The GPL itself claims to be protected by copyright, so unless the lawyer / law student thinks they have a solid argument that it's ineligible, they might be reluctant to create an unauthorised derived work. |
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Apr 12 |
answered | How can I evaluate a candidate's knowledge of Html/CSS during an interview? |
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Apr 5 |
comment |
Implementing base-10 floating point division Your multiplication is a bit overkill. You're multiplying two 9-digit numbers, so the result will have 17 or 18 digits. You then want to reduce to 9 digits, so you're dropping 8 or 9 digits. Therefore you can safely drop the bottom 3 digits from each number before multiplying, and eliminate all of the terms containing C or F. |
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Apr 4 |
revised |
Computing integration with the Trapezoidal Rule Fix scope |
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Apr 3 |
comment |
Is (1/(1/x)) always a perfect round trip? Nice use of the pigeonhole principle. It can be extended to get a bound equal to my estimate for the number of collisions. For x in (1, 2), the range (x, 2) maps onto the range (0.5, x^-1), so given the difference in ulp the proportion of collisions is at least (2 - x) - 2(x^-1 - 0.5) = 3 - x - 2x^-1. Differentiate: this has extrema when -1 + 2x^-2 = 0 i.e. x^2 = 2. Only the positive root is in range, so we get that the proportion of collisions is at least 3 - sqrt(2) - 2/sqrt(2) = 3 - 2sqrt(2). |
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Apr 2 |
awarded | Nice Answer |
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Apr 2 |
revised |
Is (1/(1/x)) always a perfect round trip? Analysis backs up empirical results |
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Apr 1 |
comment |
Is (1/(1/x)) always a perfect round trip? @MichaelShaw, there's no good reason to expect that the reciprocal should even be injective, which would be a precondition for double-reciprocal to round-trip. However, there's a difference between a) stating without proof that there's probably at least one number that doesn't round-trip; b) calculating and justifying an estimate for the number of mantissas which don't round-trip; c) proving that at least one mantissa doesn't round-trip. I would be quite interested to see a careful analysis which shows how good or bad my empirical measurement is. |
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Apr 1 |
comment |
Is (1/(1/x)) always a perfect round trip? Empirically your rule of thumb is wrong: it returns true for slightly over 80% of values of x. |
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Apr 1 |
answered | Is (1/(1/x)) always a perfect round trip? |
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Apr 1 |
comment |
Is (1/(1/x)) always a perfect round trip? You cannot conclude from the fact that 1/x can't be represented exactly that 1/(1/x) != x. To take your example, in 3.s.f. decimal floating point, 1.00 / 3.00 = 0.333, and 1.00 / 0.333 is 3.00. That particular mantissa is a fixed point of the double-reciprocal in that floating point scheme. |
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Mar 21 |
comment |
Why interviewers want Optimal Algorithms Are you sure they were doubtful about the correctness and not just wanting to see how clearly you were capable of explaining its working? |
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Mar 20 |
answered | max(x-y,0) is loop-computable |
