Thanks, but I don’t think it so strange. I never understood the use of calculus until graduate level economics, in which we had to derive the equations that would describe curves. But in real life, I never derived curves, I used preset formulas or mostly just trusted the software. And my area was never in stock calculations, maybe that is why I never encountered trig in my studies. I will read the link, and my girlfriend is an electrical engineer, I’ll get her take. Thanks for the reply.