From 04eb40b633397d03e4cbce41418626f4fabdcb02 Mon Sep 17 00:00:00 2001
From: Kouhei Yanagita <yanagi@shakenbu.org>
Date: Thu, 16 Nov 2023 20:32:53 +0900
Subject: [Bug #11183] Fix rb_complex_pow for special angles

Add a special treatment for when the argument of self is an
integral multiple of 45 degrees.

  1i ** (10 ** 100)         #=> 1+0i
  1i ** (10 ** 100 + 1)     #=> 0+1i
  (1+1i) ** (10 ** 100)     # warning: in a**b, b may be too big
                            #=> (Infinity+0.0i)
  (1+1i) ** (10 ** 100 + 1) # warning: in a**b, b may be too big
                            #=> (Infinity+Infinity*i)
---
 test/ruby/test_complex.rb | 65 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 65 insertions(+)

(limited to 'test/ruby')

diff --git a/test/ruby/test_complex.rb b/test/ruby/test_complex.rb
index edbdffd069..5cd17d9205 100644
--- a/test/ruby/test_complex.rb
+++ b/test/ruby/test_complex.rb
@@ -526,6 +526,71 @@ class Complex_Test < Test::Unit::TestCase
     r = c ** Rational(-2,3)
     assert_in_delta(0.432, r.real, 0.001)
     assert_in_delta(-0.393, r.imag, 0.001)
+  end
+
+  def test_expt_for_special_angle
+    c = Complex(1, 0) ** 100000000000000000000000000000000
+    assert_equal(Complex(1, 0), c)
+
+    c = Complex(-1, 0) ** 10000000000000000000000000000000
+    assert_equal(Complex(1, 0), c)
+
+    c = Complex(-1, 0) ** 10000000000000000000000000000001
+    assert_equal(Complex(-1, 0), c)
+
+    c = Complex(0, 1) ** 100000000000000000000000000000000
+    assert_equal(Complex(1, 0), c)
+
+    c = Complex(0, 1) ** 100000000000000000000000000000001
+    assert_equal(Complex(0, 1), c)
+
+    c = Complex(0, 1) ** 100000000000000000000000000000002
+    assert_equal(Complex(-1, 0), c)
+
+    c = Complex(0, 1) ** 100000000000000000000000000000003
+    assert_equal(Complex(0, -1), c)
+
+    c = Complex(0, -1) ** 100000000000000000000000000000000
+    assert_equal(Complex(1, 0), c)
+
+    c = Complex(0, -1) ** 100000000000000000000000000000001
+    assert_equal(Complex(0, -1), c)
+
+    c = Complex(0, -1) ** 100000000000000000000000000000002
+    assert_equal(Complex(-1, 0), c)
+
+    c = Complex(0, -1) ** 100000000000000000000000000000003
+    assert_equal(Complex(0, 1), c)
+
+    c = Complex(1, 1) ** 1
+    assert_equal(Complex(1, 1), c)
+
+    c = Complex(1, 1) ** 2
+    assert_equal(Complex(0, 2), c)
+
+    c = Complex(1, 1) ** 3
+    assert_equal(Complex(-2, 2), c)
+
+    c = Complex(1, 1) ** 4
+    assert_equal(Complex(-4, 0), c)
+
+    c = Complex(1, 1) ** 5
+    assert_equal(Complex(-4, -4), c)
+
+    c = Complex(1, 1) ** 6
+    assert_equal(Complex(0, -8), c)
+
+    c = Complex(1, 1) ** 7
+    assert_equal(Complex(8, -8), c)
+
+    c = Complex(-2, -2) ** 3
+    assert_equal(Complex(16, -16), c)
+
+    c = Complex(2, -2) ** 3
+    assert_equal(Complex(-16, -16), c)
+
+    c = Complex(-2, 2) ** 3
+    assert_equal(Complex(16, 16), c)
 
     c = Complex(0.0, -888888888888888.0)**8888
     assert_not_predicate(c.real, :nan?)
-- 
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