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[Werner]

(02-23-2016 11:29 AM)Paul Dale Wrote:  Hmmmm. I'm confused. Too long a day I think.

Working in the 39 digit internal precision.


Convert 179.9999 to radians:
179.9999 * pi/180 = 179.9999 * 0.0174532925199432957692369076848861271344
gives 3.14159090826054124413306645958873439558

sin(3.14159090826054124413306645958873439558) is
1.7453292519934434807679896054327907935835405E-6

which matches the 34S output.


What am I missing?


- Pauli

You lose precision when not performing range reduction..
SIN(3.14159090..) will have lost 6 digits of the result, (because the argument coincides with pi to 6 digits, and the range reduction will happen with radians, so subtracting pi first..) while
SIN(1e-4*pi/180) ends in 9605432786, which is the correctly rounded result.
(where Free42 gives ..787, one ulp off, due to the 34-digit DEG-RAD conversion, I think)

Werner