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2m
comment DSolve misses a solution of a differential equation
Well, I read it and liked it; hence the joke. :) Mentioning Arnol'd was a nice touch.
36m
comment DSolve misses a solution of a differential equation
Are you sure you didn't mean to publish this as an expository journal article instead of as a mere SE answer? :)
43m
comment How to achieve a decent terminator line?
@Michael, if you've seen the "day and night map" question here, that's exactly where a terminator comes in. Another instance would be the various phases of the moon.
1h
comment Implementing Picard's Iteration for solving ODEs
Okay, this code got me excited. I will have to try this the next time I see a computer…
1h
comment Speeding up the built-in Rudin-Shapiro and Thue-Morse sequence functions
@Runny, I knew I'd be asking to squeeze water from stones at some point; thanks for trying!
7h
comment Speeding up the built-in Rudin-Shapiro and Thue-Morse sequence functions
That's okay… you've been more than helpful. :)
8h
comment Speeding up the built-in Rudin-Shapiro and Thue-Morse sequence functions
In that case… what if you replace Mod[n, 2] with BitAnd[n, 1]?
8h
comment Speeding up the built-in Rudin-Shapiro and Thue-Morse sequence functions
Now that was a surprise… thanks!
8h
comment Speeding up the built-in Rudin-Shapiro and Thue-Morse sequence functions
Replacing Quotient[n, 2] with BitShiftRight[n] does not make much of a difference, right?
9h
comment How to plot a function defined by an expression containing integrals
As noted, it's hard to say anything useful if we don't see the function concerned; different integrands call for different strategies. At the lowest level, you should follow @Michael's prescription, but otherwise there is nothing to say until you edit.
10h
comment List connectivity of points in discretized mesh
First[foo] should yield the points; Cases[foo, Polygon[p_] :> p, Infinity][[1]] should give the polygon indices.
10h
comment List connectivity of points in discretized mesh
The stuff within Polygon[] looks to be useful; you'll note that it has a list of triples, corresponding to the triangle whose vertices are indexed by the integers in the triple. You should now have something to start with.
11h
comment List connectivity of points in discretized mesh
What does InputForm[foo] give you?
12h
comment Faster binary Hamming weight for big integers?
Unfortunately, I don't have a computer right now. But Jacob and me discussed this in chat; anyway, if you want to run your own tests, here are the relevant identities: ThueMorse[n] == Mod[hammingWeight[n], 2] and RudinShapiro[n] == 1 - 2 ThueMorse[BitAnd[n, Quotient[n, 2]]].
12h
comment List connectivity of points in discretized mesh
I don't have version 10 (or a computer, for that matter), but I believe the output of DiscretizeRegion[] should have a GraphicsComplex[] object in it somewhere. Can you check?
14h
comment Faster binary Hamming weight for big integers?
I guess I should add this note: this can be used to compute the Thue-Morse and Rudin-Shapiro sequences that are built-in in newer versions, but are apparently not too fast.
15h
comment Find an instance satisfying an inequality involving sums
There's always brute-force: Table[If[GammaRegularized[n + 1, p] < 0, n, ##&[]], {n, 100}].
15h
comment Find an instance satisfying an inequality involving sums
The incomplete gamma function doesn't have a closed-form inverse in this case; you'll have to resort to numerics for particular values of p.
16h
comment Find an instance satisfying an inequality involving sums
If $p$ is positive, then your sum is always positive. Negative $p$ is a different can of worms…
18h
comment How to deal with Missing[NotFound]
Look up NumberQ[] and NumericQ[].