Find Major Point of Inflection

I have a velocity graph, attached, from experimental data. I want to find the first major point of inflection before the local min at the first trough.

I have tried using... B = [0 diff(v)] Result = find(B(1:end-1).*B(2:end)<0) but it will give me all of the minor points of inflection, an artifact of the data, that I don't want, does anyone know how to do this?