how to decrease the time consumption of the code

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Abirami 2014-9-4

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编辑： Abirami 2014-9-4

Hello I've already got a lot of help in developring the encryption technique from matlab answers. Now i have another problem. I need to reduce the time consumption of the folowing part of the code.Here i generate two chaotic sequences using Chen's hyperchaotic system. I've defined a function called Chen1.m and i've given both the codes below.This part of the code is taking almost 15 minutes.Please help.Thanks in advance.

 %the values of a, b, c, d, k here
 a = 36;
 b = 3;
 c = 28;
 d = 16;
 k = 0.2;
%vector v0, which is a 4x1 vector of initial conditions
 v0 = [0.3 -0.4 1.2 1];
 fun = @(t,v) chen1(t,v,a,b,c,d,k);
 [t, v] = ode45(fun, [0 1.54], v0);
x = v(:,1);
x(257)=[];
y = v(:,2);
y(257)=[];
[lx,fx]=sort(x);
[ly,fy]=sort(y);
S=fx;
T=(fy)';
   %%matrix generated for scrambling
  [Tgrid, Sgrid] = meshgrid( T, S );
   Z = arrayfun( @(S,T) [S T], Sgrid, Tgrid, 'UniformOutput', false );
   %%scrambled matrix
   F=cellfun(@(x)  B{x(1),x(2)},Z,'un',0);
   G=cellfun(@(x)  E{x(1),x(2)},Z,'un',0);

The function is defined as follows

    function vdot = chen(t, v, a, b, c, d, k)
    x = v(1); y = v(2); z = v(3); q = v(4);
    xdot = a*(y-x);
    ydot = -(x*z)+(d*x)+(c*y)-q;
    zdot = (x*y)-(b*z);
    qdot = x+k;
    vdot = [xdot; ydot; zdot; qdot];
     end

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Adam 2014-9-4

在 MATLAB Online 中打开

First thing you should do is run the profiler on it:

profile on
functionCall(...)
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That will tell you where the bottlenecks are. One of the worst things you can do when trying to speed up code is to start focusing on really speeding up a piece of code that only takes 1% of the total running time anyway.

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Answer 1

Matt J 2014-9-4

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在 MATLAB Online 中打开

Don't use cell arrays to hold B,E, F, and G. Cell arrays are slow and unnecessary for holding arrays of scalars. Once you've repaired the damage with

 B=cell2mat(B)
 E=cell2mat(E)

you should also replace this code segment

    Z = arrayfun( @(S,T) [S T], Sgrid, Tgrid, 'UniformOutput', false );
     %%scrambled matrix
     F=cellfun(@(x)  B{x(1),x(2)},Z,'un',0);
     G=cellfun(@(x)  E{x(1),x(2)},Z,'un',0);

with this