On Sep 14, 7:24�pm, mikelee101 <mikelee101athotmaildotcom wrote:
Hello All,
I was just curious why I wasn't getting zero for the result of the cosine of
a 90 degree angle. �This formula

=COS(RADIANS(90))

returns

6.12574E-17

when I would have expected 0. �Am I misusing a function in there somewhere? �
Any thoughts would be greatly appreciated.

Excel 07, XPPro SP3.

I expect its because 0.5 * Pi has no exact binary representation, so
its only approximate. Its accuracy is only to the 63-bit accuracy of
the maths calculations in the processor.

I think that 2**-63 is not far off 10**-17.

Alan Lloyd