diff options
| -rw-r--r-- | ChangeLog | 4 | ||||
| -rw-r--r-- | ext/bigdecimal/lib/bigdecimal/math.rb | 11 |
2 files changed, 15 insertions, 0 deletions
@@ -1,3 +1,7 @@ +Wed Sep 23 21:25:20 2009 Nobuyoshi Nakada <nobu@ruby-lang.org> + + * ext/bigdecimal/lib/bigdecimal/math.rb (atan): refined. + Wed Sep 23 17:08:30 2009 Nobuyoshi Nakada <nobu@ruby-lang.org> * parse.y (assign_in_cond): also should warn assignment to dvar in diff --git a/ext/bigdecimal/lib/bigdecimal/math.rb b/ext/bigdecimal/lib/bigdecimal/math.rb index 2771c77b6f..dbc058b0b3 100644 --- a/ext/bigdecimal/lib/bigdecimal/math.rb +++ b/ext/bigdecimal/lib/bigdecimal/math.rb @@ -121,6 +121,15 @@ module BigMath def atan(x, prec) raise ArgumentError, "Zero or negative precision for atan" if prec <= 0 return BigDecimal("NaN") if x.infinite? || x.nan? + pi = PI(prec) + if neg = x < 0 + x = -x + end + if x == 1 + return pi / (neg ? -4 : 4) + elsif inv = x > 1 + x = 1 / x + end n = prec + BigDecimal.double_fig y = x d = y @@ -134,6 +143,8 @@ module BigMath y += d r += 2 end + y = pi / 2 - y if inv + y = -y if neg y end |