Issue #5178 has been reported by Marc-Andre Lafortune.

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Bug #5178: Complex#rationalize should rationalize
http://redmine.ruby-lang.org/issues/5178

Author: Marc-Andre Lafortune
Status: Open
Priority: Normal
Assignee: 
Category: core
Target version: 
ruby -v: r32354


Complex#rationalize currently calls `to_r` on the real part instead of `rationalize`:

  f = 1/3.0
  c = Complex(f)
  c.to_r == f.to_r                # => true
  c.rationalize == f.rationalize  # => false

Should I not commit this to 1.9.3 too?


diff --git a/complex.c b/complex.c
index 78f0902..1b76074 100644
--- a/complex.c
+++ b/complex.c
@@ -1335,7 +1335,8 @@ nucomp_to_f(VALUE self)
  * call-seq:
  *    cmp.to_r  ->  rational
  *
- * Returns the value as a rational if possible.
+ * If the imaginary part is exactly 0, returns the real part as a Rational,
+ * otherwise a RangeError is raised.
  */
 static VALUE
 nucomp_to_r(VALUE self)
@@ -1354,14 +1355,22 @@ nucomp_to_r(VALUE self)
  * call-seq:
  *    cmp.rationalize([eps])  ->  rational
  *
- * Returns the value as a rational if possible.  An optional argument
- * eps is always ignored.
+ * If the imaginary part is exactly 0, returns the real part as a Rational,
+ * otherwise a RangeError is raised.
  */
 static VALUE
 nucomp_rationalize(int argc, VALUE *argv, VALUE self)
 {
+    get_dat1(self);
+
     rb_scan_args(argc, argv, "01", NULL);
-    return nucomp_to_r(self);
+
+    if (k_inexact_p(dat->imag) || f_nonzero_p(dat->imag)) {
+       VALUE s = f_to_s(self);
+       rb_raise(rb_eRangeError, "can't convert %s into Rational",
+                StringValuePtr(s));
+    }
+    return rb_funcall(dat->real, rb_intern("rationalize"), argc, argv);
 }



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