Receiving mtimes error for passing vector through a function and I don't know why. Help?

x = -20:30; y = exp(2*sin(0.4*x))*5*cos(4*x);

plot(x,y)

Answer 1

[Honglei Chen]

You need to use .*

y = exp(2*sin(0.4*x))*5 .* cos(4*x);

[Victor]

thank you! I was putting after the exp().

Why does it need to be after the 5?

[Honglei Chen]

You can think of anything before 5 is a row vector and then everything after 5 is another row vector. To multiply two vectors together, you need the .* there. If you put it in front of 5, since at that time MATLAB is evaluating a multiplication between a vector and a scalar, it doesn't help. Once it finishes 5, it still encounter the same situation. If you have to put it in front of 5, then you need to group 5 and cos(4*x) together with a parenthesis.