MATLAB: Question about column operator vectors

Question

Why does vec = -1:-5 not output -1 -2 -3 -4 -5? Why does it say 1×0 empty double row vector? An explanation of this would be great. Thank you!

Answer 1

Doc says

x = j:k creates a unit-spaced vector x with elements [j,j+1,j+2,...,j+m] ...

x = j:i:k creates a regularly-spaced vector x using i as the increment ...

Thus the default value of the step, i, is +1 (one).

>> vec = -1:+1:-5 
vec =
  1×0 empty double row vector

and

>> vec = -1:+5
vec =
    -1     0     1     2     3     4     5