mrkn	2010-08-27 12:51:56 +0900 (Fri, 27 Aug 2010)

  New Revision: 29115

  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=29115

  Log:
    * math.c (math_atan2): change the behavior when x and y are zero.
    * test/ruby/test_math.rb (test_atan2): add tests for the above
      changes.

  Modified files:
    trunk/ChangeLog
    trunk/math.c
    trunk/test/ruby/test_math.rb

Index: math.c
===================================================================
--- math.c	(revision 29114)
+++ math.c	(revision 29115)
@@ -55,7 +55,13 @@
     Need_Float2(y, x);
     dx = RFLOAT_VALUE(x);
     dy = RFLOAT_VALUE(y);
-    if (dx == 0.0 && dy == 0.0) domain_error("atan2");
+    if (dx == 0.0 && dy == 0.0) {
+	if (!signbit(dx))
+	    return DBL2NUM(dy);
+        if (!signbit(dy))
+	    return DBL2NUM(M_PI);
+	return DBL2NUM(-M_PI);
+    }
     if (isinf(dx) && isinf(dy)) domain_error("atan2");
     return DBL2NUM(atan2(dy, dx));
 }
Index: ChangeLog
===================================================================
--- ChangeLog	(revision 29114)
+++ ChangeLog	(revision 29115)
@@ -1,3 +1,10 @@
+Fri Aug 27 12:47:44 2010  Kenta Murata  <mrkn@m...>
+
+	* math.c (math_atan2): change the behavior when x and y are zero.
+
+	* test/ruby/test_math.rb (test_atan2): add tests for the above
+	  changes.
+
 Fri Aug 27 12:26:23 2010  NAKAMURA Usaku  <usa@r...>
 
 	* object.c (rb_obj_class): remove mention of obsolete method.
Index: test/ruby/test_math.rb
===================================================================
--- test/ruby/test_math.rb	(revision 29114)
+++ test/ruby/test_math.rb	(revision 29115)
@@ -17,7 +17,10 @@
   end
 
   def test_atan2
-    assert_raise(Math::DomainError) { Math.atan2(0, 0) }
+    check(+0.0, Math.atan2(+0.0, +0.0))
+    check(-0.0, Math.atan2(-0.0, +0.0))
+    check(+Math::PI, Math.atan2(+0.0, -0.0))
+    check(-Math::PI, Math.atan2(-0.0, -0.0))
     assert_raise(Math::DomainError) { Math.atan2(Float::INFINITY, Float::INFINITY) }
     assert_raise(Math::DomainError) { Math.atan2(Float::INFINITY, -Float::INFINITY) }
     assert_raise(Math::DomainError) { Math.atan2(-Float::INFINITY, Float::INFINITY) }

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