[gnome-calculator/gnome-3-18] Check if base or exponent are complex for xpowy() method

[Alberto Ruiz <aruiz src gnome org>]

commit f5357f39b2ba663f1c01a83c4981271e48c8da90
Author: Alberto Ruiz <aruiz gnome org>
Date:   Mon Dec 28 16:12:32 2015 +0000

    Check if base or exponent are complex for xpowy() method
    
    Fixes #757657

 lib/number.vala          |    6 ++++++
 tests/test-equation.vala |    2 ++
 2 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/lib/number.vala b/lib/number.vala
index 8f94a40..0b09248 100644
--- a/lib/number.vala
+++ b/lib/number.vala
@@ -498,6 +498,12 @@ public class Number : Object
             return new Number.integer (0);
         }
 
+        /* base or exponent are complex */
+        if (is_complex () || y.is_complex ())
+        {
+            return pwr (y);
+        }
+
         if (!y.is_integer ())
         {
             var reciprocal = y.reciprocal ();
diff --git a/tests/test-equation.vala b/tests/test-equation.vala
index b5d46d4..80b3898 100644
--- a/tests/test-equation.vala
+++ b/tests/test-equation.vala
@@ -560,6 +560,8 @@ private void test_equations ()
     test ("i×i", "−1", 0);
     test ("i÷i", "1", 0);
     test ("1÷i", "−i", 0);
+    test ("i^2", "−1", 0);
+    test ("(−1)^(1/2)", "i", 0);
     test ("|i|", "1", 0);
     test ("|3+4i|", "5", 0);
     test ("arg 0", "", ErrorCode.MP);