A combination of underlying secular growth and the possibility of improving cyclical growth makes this stock a buy.Investors often talk about growth stocks in terms of their cyclical growth (tied to the economy) and secular growth (benefiting from a structural and fundamental change in an industry). The distinction is beneficial to understand when looking at machine vision company Cognex (CGNX 0.27%).Cognex has a big futureIt's no secret that the increasing adoption of technologies like automation and machi ...