Unable to perform assignment

Asked by Samson on 28 Jun 2019

Latest activity Edited by Jan on 28 Jun 2019

Accepted Answer by Jan

11 views (last 30 days)

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

Products

Simulink

Release

R2018b

1 Answer

Link

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;
   ...

You are now following this question

Samson (view profile)

Unable to perform assignment

Samson (view profile)

Jan (view profile)