From 96299cbf09bdb75e4d6c6849c9c4c3ce000a6fc5 Mon Sep 17 00:00:00 2001
From: Anhgelus Morhtuuzh <william@herges.fr>
Date: Mon, 10 Nov 2025 12:27:21 +0100
Subject: feat(parser): supports literal decimal numbers

---
 lib/math/calc.ex | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 lib/math/calc.ex

(limited to 'lib/math/calc.ex')

diff --git a/lib/math/calc.ex b/lib/math/calc.ex
new file mode 100644
index 0000000..7dc5fcc
--- /dev/null
+++ b/lib/math/calc.ex
@@ -0,0 +1,28 @@
+defmodule ElixirMathParser.Math.Calc do
+  alias ElixirMathParser.Math.Rational
+  def factorial(n), do: factorial_rec(n, 1)
+  defp factorial_rec(n, acc) when n > 0, do: factorial_rec(n - 1, acc * n)
+  defp factorial_rec(0, acc), do: acc
+
+  def pow(value, exponent), do: pow_rec(value, exponent, Rational.new(1))
+
+  defp pow_rec(value, exponent, acc) when is_integer(exponent) do
+    case exponent do
+      0 ->
+        acc
+
+      _ when exponent < 0 ->
+        pow_rec(Rational.new(1, value), -exponent, acc)
+
+      _ when Kernel.rem(exponent, 2) == 0 ->
+        pow_rec(Rational.mult(value, value), Kernel.div(exponent, 2), acc)
+
+      _ ->
+        pow_rec(
+          Rational.mult(value, value),
+          Kernel.div(exponent - 1, 2),
+          Rational.mult(acc, value)
+        )
+    end
+  end
+end
-- 
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