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 --- ChangeLog | 6 ++++++ ext/bigdecimal/lib/bigdecimal/math.rb | 6 +++++- 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index b0c4ef529..ff359dc1e 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +Thu Sep 24 02:08:35 2009 Nobuyoshi Nakada + + * 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]. + Thu Sep 24 01:14:18 2009 Yutaka Kanemoto * dln.c (aix_loaderror): fixed typo. suppress warnings. 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