diff --git a/config/config.exs b/config/config.exs
deleted file mode 100644
index 312f27b..0000000
--- a/config/config.exs
+++ /dev/null
@@ -1,30 +0,0 @@
-# This file is responsible for configuring your application
-# and its dependencies with the aid of the Mix.Config module.
-use Mix.Config
-
-# This configuration is loaded before any dependency and is restricted
-# to this project. If another project depends on this project, this
-# file won't be loaded nor affect the parent project. For this reason,
-# if you want to provide default values for your application for
-# 3rd-party users, it should be done in your "mix.exs" file.
-
-# You can configure for your application as:
-#
-#     config :math, key: :value
-#
-# And access this configuration in your application as:
-#
-#     Application.get_env(:math, :key)
-#
-# Or configure a 3rd-party app:
-#
-#     config :logger, level: :info
-#
-
-# It is also possible to import configuration files, relative to this
-# directory. For example, you can emulate configuration per environment
-# by uncommenting the line below and defining dev.exs, test.exs and such.
-# Configuration from the imported file will override the ones defined
-# here (which is why it is important to import them last).
-#
-#     import_config "#{Mix.env}.exs"
diff --git a/lib/math.ex b/lib/math.ex
index 709d5f1..d82492c 100644
--- a/lib/math.ex
+++ b/lib/math.ex
@@ -583,7 +583,7 @@ defmodule Math do
     new_points =
       control_points
     |> Enum.with_index()
-    |> Enum.slice(0..-2)
+    |> Enum.slice(0..-2//1)
     |> Enum.map(
       fn {p0, index} ->
           next_index = index + 1
diff --git a/test/math_test.exs b/test/math_test.exs
index 9cee28e..b672966 100644
--- a/test/math_test.exs
+++ b/test/math_test.exs
@@ -175,14 +175,6 @@ defmodule MathTest do
     assert_raise ArithmeticError, fn -> isqrt(-2) end
   end
 
-  test "mod_inv" do
-    assert_raise ArgumentError, fn -> mod_inv(1.0, 3.5) end
-  end
-
-  test "mod_inv!" do
-    assert_raise ArgumentError, fn -> mod_inv!(1.0, 3.5) end
-  end
-
   test "interpolation" do
     p0 = {0, 0}
     p1 = {1, 1}