# Demo entry 6320034

Fixed point iteration of a Julia set

Submitted by anonymous on Nov 08, 2016 at 17:25
Language: Matlab. Code size: 1.4 kB.

```clear; clf;

c = -0.778-.116i;
jiteration(c, 'jit1.gif');

c = .274-0.008i;
jiteration(c, 'jit2.gif');

function f = jiteration(c, filename)
% Initialize c, z, r, and the function

A=1.5;
N=1000;
x_vec=-A+[0:N]/N*2*A; y_vec=x_vec;

for i=1:length(x_vec)
for j=1:length(y_vec)
x(i,j)=x_vec(i); y(i,j)=y_vec(j);
end;
end;

z = x+sqrt(-1)*y;
f = @(z) z.^2 + c;
r=200;

% Iterate 25 function calls
for kk=1:25

a=abs(z);
a=min(a,1);
a=1-a;
a=(a>0);
a=a+1;
b = rot90(a);
subplot(111);
image([-A,A],[-A,A],b);
colormap([1 0 0; 1 1 1]);
axis([-A,A,-A,A]);
axis('square');
set(gca,'Fontsize',24);
xlabel('x','Fontsize',20);
ylabel('y','Fontsize',20);

c_str=num2str(c);
if c>=0
title({['Julia set for f(z) = z^2+ ',c_str];['n = ', num2str(kk)]});
else
title({['Julia set for f(z) = z^2 ',c_str];['n = ', num2str(kk)]});
end;

drawnow

% Create .gif file
F = getframe(gcf);
im = frame2im(F);
[Q,map] = rgb2ind(im,256);
if kk == 1
imwrite(Q,map,filename,'gif','LoopCount',Inf,'DelayTime',0.35);
else
imwrite(Q,map,filename,'gif','WriteMode','append','DelayTime',0.35);
end

z = f(z);
end
end
```

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