ALPHA and BETA are two physical quantities:
A is dependent variable (Y-Axis) and B is independent variable (X-Axis).
Values of ALPHA range from 50 to 250. (with steps of 50 i.e. 50, 100, 150, 200, 250 )
Values of BETA range from -2 to 3. (with steps of 1 i.e. -2, -1, 0, 1, 2, 3)...