On Nov 9, 2007 2:08 PM, Hans van Thiel <[EMAIL PROTECTED]> wrote: > Hello All, > Can anybody explain the results for 1.0, 2.0 and 3.0 times pi below? > GHCi yields the same results. I did search the Haskell report and my > text books, but to no avail. Thanks in advance, > Hans van Thiel > > Hugs> sin (0.0 * pi) > 0.0 > Hugs> sin (0.5 * pi) > 1.0 > Hugs> sin (1.0 * pi) > 1.22460635382238e-16 > Hugs> sin (1.5 * pi) > -1.0 > Hugs> sin (2.0 * pi) > -2.44921270764475e-16 > Hugs> sin (2.5 * pi) > 1.0 > Hugs> sin (3.0 * pi) > 3.67381906146713e-16 > Hugs> >
More generally, this is due to the fact that floating-point numbers can only have finite precision, so a little bit of rounding error is inevitable when dealing with irrational numbers like pi. This problem is in no way specific to Haskell. -Brent
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