* math.c (math_atan2): revive documentation before r49220.

  http://d.hatena.ne.jp/nagachika/20150112/ruby_trunk_changes_49213_49226

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49325 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 3 insertions, 1 deletions

diff --git a/math.c b/math.c
index 20b3e77cee..7c18f07181 100644
--- a/math.c
+++ b/math.c
@@ -37,7 +37,9 @@ VALUE rb_eMathDomainError;
  *  call-seq:
  *     Math.atan2(y, x)  -> Float
  *
- *  Returns a angle in radians between the positive x-axis of cartesian plane
+ *  Computes the arc tangent given +y+ and +x+.
+ *  Returns a Float in the range -PI..PI. Return value is a angle
+ *  in radians between the positive x-axis of cartesian plane
  *  and the point given by the coordinates (+x+, +y+) on it.
  *
  *  Domain: (-INFINITY, INFINITY)