From babe8ec7e7aa4654f826b1973557c712c36c72a1 Mon Sep 17 00:00:00 2001 From: nobu Date: Wed, 23 Sep 2009 17:08:37 +0000 Subject: * ext/bigdecimal/lib/bigdecimal/math.rb (atan): reduce loop with the formula of the double corner. based on a patch from Masahiro Kanai (CanI) in [ruby-dev:39367]. git-svn-id: http://svn.ruby-lang.org/repos/ruby/trunk@25062 b2dd03c8-39d4-4d8f-98ff-823fe69b080e --- ext/bigdecimal/lib/bigdecimal/math.rb | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'ext') diff --git a/ext/bigdecimal/lib/bigdecimal/math.rb b/ext/bigdecimal/lib/bigdecimal/math.rb index dbc058b0b..d1e8dbe32 100644 --- a/ext/bigdecimal/lib/bigdecimal/math.rb +++ b/ext/bigdecimal/lib/bigdecimal/math.rb @@ -125,11 +125,14 @@ module BigMath if neg = x < 0 x = -x end - if x == 1 + if x.round(prec) == 1 return pi / (neg ? -4 : 4) elsif inv = x > 1 x = 1 / x end + if dbl = x > 0.5 + x = (-1 + sqrt(1 + x**2, prec))/x + end n = prec + BigDecimal.double_fig y = x d = y @@ -143,6 +146,7 @@ module BigMath y += d r += 2 end + y *= 2 if dbl y = pi / 2 - y if inv y = -y if neg y -- cgit