long double broken on i386?

David Schultz das at FreeBSD.ORG
Tue Oct 2 10:59:56 PDT 2007


Just a quick note...

Although it would be nice to get all this stuff right the first
time, very few people are going to care if our trig functions are
accurate to within 1 ulp for huge inputs; many competing math
libraries don't guarantee that anyway. A programmer who asks for
sinl(1000000000*PI + 0.01) is going to be disappointed regardless,
because you can't represent the input accurately using IEEE-754
floating point.  Most people just care about taking a program that
uses sinl() and getting it to compile and run on FreeBSD, and most
of those programs don't call sinl() with huge arguments.

Anyway, my point is that if you have something that works
reasonably well and doesn't have egregious errors, my suggestion
is to just commit it and not kill yourself over whether the
argument reduction is correct in the last ulp.


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