Write a user-defined MATLAB function that determines the unitvector in the direction of the line that connects two points (A andB) in space. For the function name and arguments use "n =unitvec(A, B). The input to the function are two vectors A andB, each of which has three elements which are the Cartesiancoordinates of the corresponding point. The ouput is a vectorwith the three components of the unit vector in the direction fromA to B. Use the function to determine the following unitvectors:
(a) In the direction from point (1.5,2.1,4) to point(11,15,9).
(b) In the direction from point (-11,3,-2) to point(-13,-4,-5).
(c) In the direction from point (1,0,1) to point (0,1,1).