左侧和右侧具有不同数量的元素

Question

When I am trying to execute this code, I get an 'Unable to perform assignment because the left and right sides have a different number of elements.' error. Where is the problem? Thanks for helping.

A = 1250; 
Q = 450; 
t = (0:0.5:10);
y(1) = 0;
for i = 1:length(t)
    y(i+1) = y(i) + [(3*(Q/A).*sind(t).^2)-(Q/A)].*0.5;
end
display(y);

Answer 1

Inside the for loop, you assign an expression (the RHS) to an array (the LHS). y(i) is a 1x1 array, and the RHS has the same dimensions as t ( 1x21 ). You cannot assign 21 values to an array that can only hold one. To repair, I'd suggest preallocating y , with the line

y = zeros(numel(t), numel(t))

or, what I think you probably intended, only call one element of t at a time

y(i+1) = y(i) + [(3*(Q/A).*sind(t(i)).^2)-(Q/A)].*0.5;

As an aside, it is bad practice to use i as a variable as it already has a built-in value in Matlab. For loop indices I usually use ii , jj or k .