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9:07 AM
Update: didn't screw it up!
2
 
 
5 hours later…
1:59 PM
I just encountered some code that takes 16 seconds on the first call, but less than 0.01 on subsequent calls, so I guess there's some internal caching going on. Anyone know where I could read about that?
 
 
2 hours later…
3:31 PM
specifically, D[Sum[a[x[i], x[j]] n[j], {j, nsp}], x[i]] // AbsoluteTiming
 
4:10 PM
I have a sequence of integers, and I need to extract a subsequence of its high-water marks (mathworld.wolfram.com/High-WaterMark.html). Is there a simpler/faster way to do that than HighWaterMarks[s_?VectorQ] := Reap[Block[{max = -∞}, Do[If[n > max, Sow[max = n]], {n, s}]]][[2, 1]];?
 

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