Why is the vector length 7?

Learning Matlab through some simple plotting questions.

Why is the error message shown?, I don't see how Q3 has a vector length of 7. (See attached image)

Answer 1

[Walter Roberson]

What you coded as x inside your function is a vector of initial conditions, not (just) the current location on the x axis. Each place you referred to x without a subscript, you are getting the vector of length 3. You do that twice, and you have one element that does not use x, so you have an output which is 3+1+3 = 7 long.