From aeef49e9ef770fdb30ff465eeeec172a3607be76 Mon Sep 17 00:00:00 2001
From: bakk <bakk@tuta.io>
Date: Thu, 20 May 2021 19:50:59 +0200
Subject: [PATCH] Division with complex numbers

---
 kalk/src/kalk_num/mod.rs | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/kalk/src/kalk_num/mod.rs b/kalk/src/kalk_num/mod.rs
index 75e59b0..d9e5423 100644
--- a/kalk/src/kalk_num/mod.rs
+++ b/kalk/src/kalk_num/mod.rs
@@ -292,8 +292,23 @@ impl KalkNum {
     }
 
     pub(crate) fn div(self, context: &mut crate::interpreter::Context, rhs: KalkNum) -> KalkNum {
-        let right = calculate_unit(context, &self, rhs.clone()).unwrap_or(rhs);
-        KalkNum::new(self.value / right.value, &right.unit)
+        let right = calculate_unit(context, &self, rhs.clone()).unwrap_or(rhs.clone());
+
+        // Avoid unecessary calculations
+        if self.imaginary_value == 0f64 && right.imaginary_value == 0f64 {
+            KalkNum::new(self.value / right.value, &right.unit)
+        } else {
+            // Multiply both the numerator and denominator
+            // with the conjugate of the denominator, and divide.
+            let conjugate = rhs.get_conjugate();
+            let numerator = self.clone().mul(context, conjugate.clone());
+            let denominator = rhs.clone().mul(context, conjugate);
+            KalkNum::new_with_imaginary(
+                numerator.value / denominator.value.clone(),
+                &right.unit,
+                numerator.imaginary_value / denominator.value,
+            )
+        }
     }
 
     pub(crate) fn rem(self, context: &mut crate::interpreter::Context, rhs: KalkNum) -> KalkNum {
@@ -301,6 +316,14 @@ impl KalkNum {
         KalkNum::new(self.value % right.value, &right.unit)
     }
 
+    pub fn get_conjugate(&self) -> KalkNum {
+        KalkNum::new_with_imaginary(
+            self.value.clone(),
+            &self.unit,
+            self.imaginary_value.clone() * (-1f64),
+        )
+    }
+
     /// Get an estimate of what the number is, eg. 3.141592 => π
     pub fn estimate(&self) -> Option<String> {
         let fract = self.value.clone().fract().abs();