Unable to perform assignment

Asked by Samson on 28 Jun 2019

Latest activity Edited by Jan on 28 Jun 2019

Accepted Answer by Jan

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From my attached code and get the following error

Unable to perform assignment because the left and right sides have a different number of elements.

Error in aa1 (line 12)

*Y(i)yo=utput;

a= 0.2; b= 0.2; c = 5.7;
% initial condition
yo = [0.5;0.5;1];
% computing the trajectory
dt = 0.01;
tspan = (dt:dt:100);
yinput = yo;
Y = zeros(tspan(end)/dt,1);
 for i = 1: tspan(end)/dt
 time = i*dt;
 youtput = rk4angelstepb(@rosslerb,dt,yinput,a,b,c);
 Y(i) = youtput;
 yinput = youtput;
end

1 Comment

Adam on 28 Jun 2019

You can see what size things are with a breakpoint, or using the stop on errors option and testing on command line when it stops. It's a valuable resource for finding these problems. How you solve them is very situation dependent, but the error message says what is wrong and what is expected in this case.

https://uk.mathworks.com/help/matlab/matlab_prog/debugging-process-and-features.html

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Answer by Jan on 28 Jun 2019

Edited by Jan on 28 Jun 2019

Accepted Answer

If the initial condition has 3 elements: yo = [0.5;0.5;1], te evaluated trajectory will have 3 elements per time step also. Then you need most likely:

Y = zeros(3, tspan(end)/dt);
for i = 1: tspan(end)/dt
   time    = i*dt;
   youtput = rk4angelstepb(@rosslerb,dt,yinput,a,b,c);
   Y(:, i) = youtput;
   ...

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Unable to perform assignment

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