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DescripciónHalflife-sim.gif
English: Simulation of many identical atoms undergoing radioactive decay, starting with either four atoms (left) or 400 atoms (right). The number at the top indicates how many half-lives have elapsed. Note the law of large numbers: With more atoms, the overall decay is less random. Image made with Mathematica, I am happy to send the source code if you would like to make this image more beautiful, or for any other reason.
Yo, el titular de los drechos d'autor d'esta obra, la llibero como dominiu públicu. Esto s'aplica nel mundu ensembre. En dellos países seique esto nun seya posible llegalmente; nesti casu: Doi a cualesquier persona permisu pa usar esta obra pa cualesquier propósitu, ensin denguna condición, menos si eses condiciones requierense pola llei.
(* Source code written in Mathematica 6.0, by Steve Byrnes, 2010. I release this code into the public domain. *)
SeedRandom[2]
(*Build list of point coordinates and radii*)
BuildCoordList[SqCenterX_, SqCenterY_, SqSide_, PtsPerRow_] :=
Flatten[Table[{i, j}, {i, SqCenterX - SqSide/2, SqCenterX + SqSide/2, SqSide/(PtsPerRow - 1)},
{j, SqCenterY - SqSide/2, SqCenterY + SqSide/2, SqSide/(PtsPerRow - 1)}], 1];
coordslist = Join[
BuildCoordList[3.5, 1, 1.8, 20],
BuildCoordList[3.5, 3, 1.8, 20],
BuildCoordList[3.5, 5, 1.8, 20],
BuildCoordList[3.5, 7, 1.8, 20],
BuildCoordList[1, 1, .7, 2],
BuildCoordList[1, 3, .7, 2],
BuildCoordList[1, 5, .7, 2],
BuildCoordList[1, 7, .7, 2]];
NumPts = Length[coordslist];
radiuslist = Join[Table[.03, {i, 1, 4*400}], Table[.1, {i, 1, 4*4}]];
(*Draw borders*)
xlist = {0, 2};
leftx = 0;
rightx = 2;
numx = Length[xlist];
ylist = {0, 2, 4, 6, 8};
topy = 0;
boty = 8;
numy = Length[ylist];
lines = {};
For[i = 1, i <= numy, i++,
lines = Append[lines, Line[{{leftx, ylist[[i]]}, {rightx, ylist[[i]]}}]]];
For[i = 1, i <= numx, i++,
lines = Append[lines, Line[{{xlist[[i]], topy}, {xlist[[i]], boty}}]]];
xlist = {2.5, 4.5};
leftx = 2.5;
rightx = 4.5;
numx = Length[xlist];
ylist = {0, 2, 4, 6, 8};
topy = 0;
boty = 8;
numy = Length[ylist];
For[i = 1, i <= numy, i++,
lines = Append[lines, Line[{{leftx, ylist[[i]]}, {rightx, ylist[[i]]}}]]];
For[i = 1, i <= numx, i++,
lines = Append[lines, Line[{{xlist[[i]], topy}, {xlist[[i]], boty}}]]];
(*Write numbers:
I want to be able to write a number with one decimal place,
including padding with ".0" when it's an integer.*)
WriteNum[num_] := Block[{rounded}, rounded = N[Floor[num, 0.1]];
If[FractionalPart[rounded] == 0, ToString[rounded] <> "0", ToString[rounded]]];
(*Randomly choose decay times:
To get an expontial-decay-distributed random number, we pick a number uniformly between 0 and 1.
Take its negative log to get the time that it blows up, which is between 0 and infinity.
But divide by log 2 so that when the time = 1, there's 50% chance of decaying. *)
BlowTime = Table[-Log[RandomReal[]]/Log[2], {i, 1, NumPts}];
(*Draw graphics*)
GraphicsList = {};
NumFrames = 80;
TimePerFrame = .05;
Video = {};
For[frame = 1, frame <= NumFrames, frame++,
CurrentTime = (frame - 1)*TimePerFrame;
ImageGraphicsList = lines;
ImageGraphicsList =
Append[ImageGraphicsList, Text[WriteNum[CurrentTime], {.8, 8.5}, {-1, 0}]];
ImageGraphicsList =
Append[ImageGraphicsList, Text[WriteNum[CurrentTime], {3.3, 8.5}, {-1, 0}]];
For[pt = 1, pt <= NumPts, pt++,
If[CurrentTime < BlowTime[[pt]],
ImageGraphicsList = Append[ImageGraphicsList, {Blue, Disk[coordslist[[pt]], radiuslist[[pt]]]}]]];
Video = Append[Video, Graphics[ImageGraphicsList, ImageSize -> 100]];];
(*Pause at start*)
Video = Join[Table[Video[[1]], {i, 1, 5}], Video];
(*Export*)
Export["test.gif", Video, "DisplayDurations" -> {10}, "AnimationRepititions" -> Infinity ]
Pies
Añade una explicación corta acerca de lo que representa este archivo
Changed top-bottom split to left-right split, with space between; pause at start; 400 atoms in each crowded box instead of 296. (Thanks to Bdb484 for suggestions.)
{{Information |Description={{en|1=Simulation of many identical atoms undergoing radioactive decay. The number at the top indicates how many half-lives have elapsed. Note that after one half-life there are not ''exactly'' one-half of the atoms remaining, o