Merge pull request #12 from matthewtoast/master

Add constant i

lib/unicode_math/constants.rb

@@ -22,6 +22,12 @@ def self.included(base)
           end
         end
 
+        %w(𝐢 𝑖 𝒊 𝒾 𝓲 𝔦 𝕚 𝖎 𝗂 𝗶 𝘪 𝙞 𝚒).each do |i|
+          define_method(i) do
+            Complex::I
+          end
+        end
+
         define_method('∞') do
           1.0 / 0
         end

spec/unicode_math/constants_spec.rb

@@ -15,6 +15,10 @@
     expect(𝑒).to be_within(0.00005).of(2.7183)
   end
 
+  it 'defines 𝑖' do
+    expect(𝑖 * 𝑖).to eq(-1)
+  end
+
   it 'defines ∞' do
     expect(∞ + 1).to eq(∞)
   end

spec/unicode_math/equations/euler_spec.rb

@@ -0,0 +1,9 @@
+# encoding: utf-8
+
+require 'spec_helper'
+
+describe "Euler's identity" do
+  it 'elegantly relates ℯ, 𝒊, π, 1 and 0' do
+    expect((ℯ.ⁿ(𝒊*π)+1).real).to eq(0)
+  end
+end