Why this error?
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if true
% code
for j1 = 2:length(t)
q1(j1) = (rho2(j1) - rho2(j1-1))*v2(j1-1)./((rho1_final - rho2(j1))*dt);
v2(j1) = v2(j1-1) + (q1(j1)-q2)*dt;
v1(j1) = v1(j1-1) - q1(j1)*dt;
end
end
I ended up getting this error in the second line : In an assignment A(:) = B, the number of elements in A and B must be the same. What is the mistake?
10 Comments
Dennis
on 12 Jul 2018
It is way easier to answer your question if you provide the needed information. You are probably trying to assign a vector to q1(j1),v2(j1) or v1(j1). If dt is a scalar you should check if rho1_final is a scalar und if rho2() does return scalars.
In general it helps to provide the code with possible inputs, related functions (like rho2) and the complete error message - yes, knowing in which line an error occurs does sometimes help to solvee the problem.
Answers (2)
Image Analyst
on 12 Jul 2018
Try
v2(j1) = v2(j1-1) + (q1(j1) - q2(j1)) .* dt;
4 Comments
Image Analyst
on 12 Jul 2018
But Dennis already did that "It is way easier to answer your question if you provide the needed information" so I didn't think I need to repeat that, but since you didn't provide it I thought I'd give a link that is more helpful than Dennis's request. It's a link that we often give that spells out all the various things that one might provide, lest one provide only part of the things that would help.
Anyway, since you didn't read the link or follow its helpful suggestions, we still don't have all your code and can't even get to the error you mention because of the missing variables, so we're left to guess at possible reasons instead of knowing what the problem is.
Still willing to help, if you let us.
Dennis
on 13 Jul 2018
If rho2() returns a vector your calculation will result in a vector aswell.
q1(j1,:) = (rho2(j1) - rho2(j1-1))*v2(j1-1)./((rho1_final - rho2(j1))*dt);
Please consider initializing q1 so its size doesn't change in every loop iteration.
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