2,630 reputation
216
bio website mathani.tumblr.com
location
age
visits member for 1 year, 8 months
seen Nov 6 at 15:42

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
25
answered Solve and plot an equation that is dependent on a transcendental equation
May
24
revised Inverting a Spline-Function (Bezier or BSpline)
deleted 1 characters in body
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
It's a special delay. It waits until f[t] evaluates to a list of numbers. (I learnt this here.)
May
24
revised Inverting a Spline-Function (Bezier or BSpline)
added 278 characters in body
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
First, Last, I don't know which is x and which y in this case. :) Anyway, delayed FindRoot works. You may want to Quiet it here though.
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
@gwr Why do you expect t -> .72 since f[.5] gives y -> .6 in this case?
May
24
revised Inverting a Spline-Function (Bezier or BSpline)
added 219 characters in body
May
24
comment Inverting a Spline-Function (Bezier or BSpline)
FindRoot can solve this.
May
24
answered Inverting a Spline-Function (Bezier or BSpline)
May
24
comment Mapping multiple functions
@PinguinDirk MapThread! :)
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.