14. Write a user-defined MATLAB function that determines the unit vector in the direction of the line that connects two points (A and B) in space. For the function name and arguments, use n = unitvec(A,B). The input to the function are two vectors A and B, each with the Cartesian coordinates of the corresponding point. The output n is a vector with the components of the unit vector in the direction from A to B. If points A and B have two coordinates each (they are in the x y plane), then n is a two-element vector. If points A and B have three coordinate each (general points in space), then n is a three-element vector. Use the function to determine the following unit vectors:

(a) In the direction from point (–0.7, 2.1) to point (9, 18).

(b) In the direction from point (10, –3.5, –2.5) to point (–11, 6.5, 5.9).