What does this error mean?

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

Error in lab26_kpetting (line 46)

acc(idx) = (px(idx)-Ffriction)/mass;

Answer 1

[Image Analyst]

If idx is a single number, then acc(idx) needs to be a single number. Evidently something in your expression is an array. Try this:

idx
size(idx)
size(px(idx))
size(Ffriction)
size(mass)

What do you see? One of them does not have a size of 1. It's not a scalar. One of them is an array with multiple elements.

Or else Ffriction doesn't have the same number of elements as idx.