v is calculated in counts per millisecond with m_cpi is 0.

When m_cpi is > 0 it uses centimeters per second.

I recommend WinPlot for analyzing various curves and things:

http://math.exeter.edu/rparris/winplot.html

Just use v as your x so for example: f(x) = 5 + (0.1(x-0))^(3-1)