Bad Math!!

willthedancer said:
FYI, the errors in the trig algorithm are in the second and third decimal places. The results from the steel supplier had a second harmonic in my cosine curve.
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Makes you wonder how the heck that happened. Almost sounds like a floating point math error in the processor.
 
I think it is just a sick algorithm, rather than using a table. It's not across the board, but creates a second harmonic in the sine curve. It's worse in the tangent and arctan functions. My buddy has a kid in middle school, and this cropped up a couple of weeks ago during homework. I didn't quantify that one, but they noted errors when using the calculator. Since my CAD is cardboard aided design, I have not quantified that one other than in an 8" circle cut at a 30 degree angle the error in the cosine curve was a harmonic that was about 3/16 of an inch. Since I was welding that tube onto a plate, it wasn't too good to have it 7 degrees off and a 3/8 gap in two places.

Jim2, It's easy to verify this with a little trig table and a calculator with scientific functions. I can't speak for what brands, but the ones back in the '90s were Sharp Elsimates. I don't know what my buddy's kid is using, but likely is TI.
 
Even my calculator app on my phone is sick.

Sent from my MotoE2(4G-LTE) using Tapatalk
 
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