mirror/musl - mirror of git://git.musl-libc.org/musl

	Commit message (Collapse)	Author	Age	Files	Lines
*	math: change the formula used for acos.s	nsz	2012-05-05	1	-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)
*	acos.s fix: use the formula acos(x) = atan2(sqrt(1-x),sqrt(1+x))	nsz	2012-03-22	1	-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.
*	use alternate formula for acos asm to avoid loss of precision	Rich Felker	2012-03-19	1	-3/+11
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*	asm for inverse trig functions	Rich Felker	2012-03-19	1	-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.