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seen Jun 17 at 8:07

honeycomb decay

Mathematica can save time delays between frames together with animated GIF (look for "DisplayDurations" under options of GIF format). This in turn allowed me to produce exactly 28 frames for the decay of this honeycomb with 28 cells. Modelling radioactive decay, where for example time intervals between clicks on a Geiger counter are approximately exponentially distributed, I can simulate the delays (rounded and shifted to run from t1/100-th seconds with average value (t1+t0)/100-th seconds) as:

delays[{t1_, t0_}, n_] :=
 t1 + Round[
   RandomVariate[ExponentialDistribution[1/t0], n]]

I set t1=2 here. Most browser can't present a delay of 2/100-th seconds properly. Chrome can.


May
24
comment Constraining solution's sign with NSolve
@pablo With FindRoot you must provide starting values, seeds. You may want to automate that. See this answer which also links to such function FindAllCrossings2D[] in particular.
May
24
answered Constraining solution's sign with NSolve
May
24
comment Constraining solution's sign with NSolve
@pablo You may switch to FindRoot. How would you specify x > 0 then?
May
24
comment Constraining solution's sign with NSolve
Solve everything and then Select desired solutions?
May
24
revised Mapping multiple functions
deleted 19 characters in body
May
24
comment Embed Code Into Image
If image is intended for web and HTML only, you can write its code in the alt or title attribute of img tag.
May
24
answered Mapping multiple functions
May
21
comment extracting the rows of a matrix satisfying a condition (e.g. all elements negative)
@Mr.Wizard 0.093601
May
20
comment extracting the rows of a matrix satisfying a condition (e.g. all elements negative)
@Mr.Wizard It must be clocking and a newer model I guess, mine is a bit old already (2009) and running at 2.93 GHz. My times are {0.952, 0.0780, 1.84, 2.04} which make approximately same ratios as yours, somewhere 10 : 1 : 25 : 30. P.S. Pick with UnitStep is the fastest here with 0.047.
May
20
comment extracting the rows of a matrix satisfying a condition (e.g. all elements negative)
I'm curious, what computer do you run? For Pick picks a second almost on my i7 (+ Win7 and Mma 9). Can I tweak my system any towards the performance of yours? Another slower method, by a factor of 3.5 with my timing, is to: Scan with levelspec {-2} and Sow rows with negative third element.
May
18
comment How to get a solution set of a nonlinear system of equations?
@J.M. Yes, that's a truly great post and discussion. Should a beginner be pointed to a post like that however, it could scare him s******* easily, no?
May
18
answered How to get a solution set of a nonlinear system of equations?
May
17
revised Tricky selection of elements based on their position
added 160 characters in body
May
17
answered Tricky selection of elements based on their position
May
17
accepted NDSolve with vector function
May
15
revised NDSolve with vector function
added 10 characters in body
May
15
asked NDSolve with vector function
May
15
comment Plotting points and functions in one graphic
Look Epilog in help.
May
15
revised How to select elements from a 4D Array?
deleted 4 characters in body
May
15
comment How to select elements from a 4D Array?
@J.M. BlockRandom[...] for example, I know that. Chances are with that many elements there will be at least one 42. :)