Re: Graphical Ray tracing on Hangar Floor



On Dec 11, 10:01 pm, "Grandpa" <j.ray...@xxxxxxxx> wrote:
Jim Klein wrote:
Probably with a set of 7 place trig tables and Snell's law and a
mechanical desk calculator. It sounds pretty terrible now but as late
as the 1950's people used 7 place trig tables and a mechanical
calculator like a Marchant or a Frieden. Square roots we performed
iteratively with plus, minus, multiply and divide. In 1947, or before, smart lens designers in England had discarded trig
tables, trig functions and trigonometry altogether from ray-tracing.
They were using algebraic equations similar to Kingslake's "(Q,U)
method" without messing with sines and cosines . Square roots were
obtained to 6 places with the help of a 3-place table, that fit in on
page, and with a single division. And in 1951, in the US, there was a
Friden mechanical calculator that extracted square roots, and oh yes,
it made a pretty terrible noise, just like a machine gun. I used one of
them, it did not bother me because I was losing my hearing already, but
poor Dr. K. Pestrekov who shared the office with me...

Grandpa.

Grandpa, I was waiting for your reply on the topic.

This was pre 1945 the folklore goes.

I did look up the Friden mechanical calculators you and Jim were
talking about on google image.
Glad I didnt sit near you then.

No wonder you wrote Eikonal in software as soon as possible.

.

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