musl - musl - an implementation of the standard library for Linux-based systems

Age	Commit message (Collapse)	Author	Lines
2012-05-05	math: change the formula used for acos.s	nsz	-10/+8
	old: 2atan2(sqrt(1-x),sqrt(1+x)) new: atan2(fabs(sqrt((1-x)(1+x))),x) improvements: * all edge cases are fixed (sign of zero in downward rounding) * a bit faster (here a single call is about 131ns vs 162ns) * a bit more precise (at most 1ulp error on 1M uniform random samples in [0,1), the old formula gave some 2ulp errors as well)
2012-03-22	acos.s fix: use the formula acos(x) = atan2(sqrt(1-x),sqrt(1+x))	nsz	-3/+1
	the old formula atan2(1,sqrt((1+x)/(1-x))) was faster but could give nan result at x=1 when the rounding mode is FE_DOWNWARD (so 1-1 == -0 and 2/-0 == -inf), the new formula gives -0 at x=+-1 with downward rounding.
2012-03-20	x86_64 math asm, long double functions only	Rich Felker	-0/+20
	this has not been tested heavily, but it's known to at least assemble and run in basic usage cases. it's nearly identical to the corresponding i386 code, and thus expected to be just as correct or just as incorrect.