Dear WW: thank you for your excessively kind words. At math I'm just barely out of the dunce class. My older brother could do problems in his head almost instantly that took me five minutes on paper. I had a physics class with prof named Newton Henry Black (three physicists in one name)and we had a dozen such problems every day for a year. Enough repetition that dunce as I am at math, I can still do that kind of problem. But not in my head.