From 745a2aac690ef026ffd8a3c1ca82ddc61d6babe6 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Tue, 12 Jul 2016 14:13:46 +0000
Subject: math.c: Complex sqrt

* math.c (rb_math_sqrt): [EXPERIMENTAL] move Complex sqrt support
  from mathn.rb.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55646 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 math.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'math.c')

diff --git a/math.c b/math.c
index 750a520c9b..8d36389a28 100644
--- a/math.c
+++ b/math.c
@@ -587,9 +587,24 @@ math_log10(VALUE obj, VALUE x)
 
 static VALUE
 math_sqrt(VALUE obj, VALUE x)
+{
+    return rb_math_sqrt(x);
+}
+
+VALUE
+rb_math_sqrt(VALUE x)
 {
     double d;
 
+    if (RB_TYPE_P(x, T_COMPLEX)) {
+	int neg = signbit(RCOMPLEX(x)->imag);
+	double re = Get_Double(RCOMPLEX(x)->real), im;
+	d = Get_Double(rb_complex_abs(x));
+	im = sqrt((d - re) / 2.0);
+	re = sqrt((d + re) / 2.0);
+	if (neg) im = -im;
+	return rb_complex_new(DBL2NUM(re), DBL2NUM(im));
+    }
     d = Get_Double(x);
     /* check for domain error */
     if (d < 0.0) domain_error("sqrt");
-- 
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