Add Next And Previous Floats as a ruby til.

README.md

@@ -111,6 +111,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 - [Finding The Source of Ruby Methods](ruby/finding-the-source-of-ruby-methods.md)
 - [Limit Split](ruby/limit-split.md)
 - [Listing Local Variables](ruby/listing-local-variables.md)
+- [Next And Previous Floats](ruby/next-and-previous-floats.md)
 - [Override The Initial Sequence Value](ruby/override-the-initial-sequence-value.md)
 - [Parallel Bundle Install](ruby/parallel-bundle-install.md)
 - [Passing Arbitrary Methods As Blocks](ruby/passing-arbitrary-methods-as-blocks.md)

ruby/next-and-previous-floats.md

@@ -0,0 +1,38 @@
+# Next And Previous Floats
+
+The `Float` class has two interesting methods for stepping forward or
+backwards through the numbers that can actually be *represented* by floats.
+This is handy since floats are not evenly spaced.
+
+Use `#next_float` to go forward
+
+```ruby
+> 2.0
+=> 2.0
+> _.next_float
+=> 2.0000000000000004
+> _.next_float
+=> 2.000000000000001
+> _.next_float
+=> 2.0000000000000013
+> _.next_float
+=> 2.0000000000000018
+```
+
+Use `#prev_float` to go backwards
+
+```ruby
+> 2.0
+=> 2.0
+> _.prev_float
+=> 1.9999999999999998
+> _.prev_float
+=> 1.9999999999999996
+> _.prev_float
+=> 1.9999999999999993
+> _.prev_float
+=> 1.9999999999999991
+```
+
+I cannot think of any practical use cases, but it is fun to know they are
+there if you need them.