Beware not to buy HP Prime, if you are engineer!

[Luigi Vampa]

I have seldom (if ever) used to lean on HP48/49/50 equations' libraries. Although they are an impressive collection, I have always felt most of them don't dive deep enough in the subject at hand. I prefer to know the core equations and constants. For me they are simply nice to have, especially when you happen to need some 'collateral knowledge'... seldom in my case. Besides, I prefer to write my own 'ad hoc' programs.
It is all up to which tool you enjoy the most; but the production of human endorphins is really a subjective matter.