Function Drange
(
drange < n > < from > < to > &optional (shift
0) )
Creates a column vector of length n, with elements of equal spacing
between from and to. The shift is the a number between 0 and 1 and
shifts the start position.
For example: (drange 4 0 1) -> 0 1 2 3, while
(drange 4 0 1 0.5) -> 0.5 1.5 2.5 3.5.