I wrote CAD software for a while and became an expert in Trig ... I have to say that the point where a branch of mathematics becomes intuitive is a real epiphan

I wrote CAD software for a while and became an expert in Trig ... I have to say that the point where a branch of mathematics becomes intuitive is a real epiphany. I also used mathe pretty heavily working on QAM modulator designs for the cable television industry. And yet in almost thirty-five years of engineering I really only remember using Calculus once (to adjust some tables we used to calculate Bessel filter component values).