Robert Kern wrote: > Christopher Barker wrote: >> I wonder if there are any C math libs that do a better job than you'd >> expect from standard FP? (short of unlimited precision ones) > > With respect to π and the zeros of sin() and cos()? Not really. If > numpy.sin(numpy.pi) were to give you 0.0, it would be *wrong*. numpy.sin() is > supposed to give you the most accurate result representable in > double-precision > for the input you gave it.
But does it? > numpy.pi is not π. More precisely, it's the best IEEE754 64 bit FP approximation of pi. Right. I think that was the trick that HP used -- they somehow stored and worked with pi with more digits. The things you can do if you're making dedicated hardware. I do wonder if there would be some way to use the extended precision built in to Intel FP hardware -- i.e. have a pi that you can pass in that has the full 80 bits that can be used internally. I don't know if the trig functions can be done with extended precision though. -Chris -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception [EMAIL PROTECTED] _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
