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02 Oct 2012 Animations Some animation in MATLAB Author: Ankur Pawar Anton Semechko

Hi Ankur,

your submission inspired this:

http://www.mathworks.com/matlabcentral/fileexchange/38473-belousov-zhabotinsky-reaction-on-2-manifold

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01 Oct 2012 Animations Some animation in MATLAB Author: Ankur Pawar Anton Semechko

Hi Ankur. I made some changes to your BZanimation script that make it run much faster. Specifically, I vectorized two of the innermost loops using linear indices.

function BZreaction
%BZreaction animation
%Belousov-Zhabotinsky Reaction animation
%This MATLAB code is converted from Processing code available in this link
%http://www.aac.bartlett.ucl.ac.uk/processing/samples/bzr.pdf

%version 2. Corrected the drift of pixels as suggested
% by Jonh.

xres=256; %x resolution
yres=256; %y resolution

a=rand(xres,yres,2);
b=rand(xres,yres,2);
c=rand(xres,yres,2);
p = 1;
q = 2;
img=zeros(xres,yres,3);

mm = mod((1:xres+2)+xres,xres)+1;
nn = mod((1:yres+2)+yres,yres)+1;
[mm,nn]=meshgrid(mm,nn);
idx=sub2ind([yres xres],nn(:),mm(:));
idx=reshape(idx,[yres xres]+2);

figure
for k=1:1000

c_a = zeros(xres,yres);
c_b = zeros(xres,yres);
c_c = zeros(xres,yres);

for m=1:xres
for n=1:yres

idx_temp=idx(m:m+2,:);
idx_temp=idx_temp(:,n:n+2);
idx_temp=idx_temp(:);
if p==2
idx_temp=idx_temp+(xres+0)*(yres+0);
end

c_a(m,n) =c_a(m,n)+ sum(a(idx_temp));
c_b(m,n) =c_b(m,n)+ sum(b(idx_temp));
c_c(m,n) =c_c(m,n)+ sum(c(idx_temp));

end
end

%correction of pixel drift
c_a = circshift(c_a,[2 2]);
c_b = circshift(c_b,[2 2]);
c_c = circshift(c_c,[2 2]);

c_a =c_a/ 9.0;
c_b =c_b/ 9.0;
c_c =c_c/ 9.0;

a(:,:,q) = double(uint8(255*(c_a + c_a .* (c_b - c_c))))/255;
b(:,:,q) = double(uint8(255*(c_b + c_b .* (c_c - c_a))))/255;
c(:,:,q) = double(uint8(255*(c_c + c_c .* (c_a - c_b))))/255;

img(:,:,1)=c(:,:,q);
img(:,:,2)=b(:,:,q);
img(:,:,3)=a(:,:,q);

if p == 1
p = 2; q = 1;
else
p = 1; q = 2;
end

image(uint8(255*hsv2rgb(img)))
axis equal off
drawnow
end

Comment only
11 Mar 2012 Animations Some animation in MATLAB Author: Ankur Pawar John Bullinga

The BZ animation has a drift of two pixels up and left per cycle that may be corrected by adding

c_a = circshift(c_a,[2 2]);
c_b = circshift(c_b,[2 2]);
c_c = circshift(c_c,[2 2]);

before the 'c_a =c_a/ 9.0;' line

Comment only
30 Oct 2011 Points On Line Linearly spaced points between two point and ,point in Convex Hull test. Author: Ankur Pawar Ankur Pawar

It is generalized but not fast.

tic,points = pointsOnLine([2 4 5],[9 9 9],500);toc
Elapsed time is 0.000351 seconds

tic,points = interp1([0;1], [2 4 5;9 9 9], linspace(0,1,500));toc
Elapsed time is 0.001596 seconds

Comment only
18 Oct 2011 Points On Line Linearly spaced points between two point and ,point in Convex Hull test. Author: Ankur Pawar Sven

Sven (view profile)

Please note that this function can be generalised with a speedup by:

points = interp1([0;1], [point1;point2], linspace(0,1,numPoints));

Comment only
18 Nov 2009 Attractor Quadratic attractor,Clifford attractor,Peter De Jong generated using histogram method. Author: Ankur Pawar Thomas Clark

I'll admit, this is cool looking (hence 2 stars), but to be honest, I don't feel it's satisfactory on other counts.

A good file exchange submission is likely to meet several (not necessarily all) of the following criteria:
- be a function which can be easily adapted for other purposes.
- be a function which can be used 'out-of-the-box' for some useful purpose.
- be well commented, including a description of the algorithm used, inputs and outputs, example usage, and comments interleaved with the code so the reader knows what's going on.
- demonstrate a principle or programming technique
- be well programmed (e.g. avoid the use of nested for-loops, use as-simple-as-possible programmatic structure etc).

This submission meets none of those criteria, although I'd encourage the author to comment it more carefully, as I feel that the strange attractor is a tool which is poorly understood. Clearly the author has a good grasp of their application, and if communicated well, this could be very useful for the matlab community.

2
29 Jul 2009 Newton fractal These scripts generate 7 different Newton fractals. Author: Ankur Pawar Diyashvir Kreetee Rajiv Babajee

Hi very good program.
I would like to have only 3 colors to display the fractals (one color for each root).
n black color for diverging points. I wil appreciate if you can give some suggestions.

5
23 Jul 2009 high resolution Mandelbrot set and Julia set ( 2000x2000 pixel ) Plot Julia set and Mandelbrot set in 2 seconds Author: Ankur Pawar Roland Pfister

Roland Pfister (view profile)

Well done!

5

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