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.
2012-03-19	use alternate formula for acos asm to avoid loss of precision	Rich Felker	-3/+11

2012-03-19	asm for inverse trig functions	Rich Felker	-0/+24
	unlike trig functions, these are easy to do in asm because they do not involve (arbitrary-precision) argument reduction. fpatan automatically takes care of domain issues, and in asin and acos, fsqrt takes care of them for us.