From 347cc501195802939189e48577b2214264af2808 Mon Sep 17 00:00:00 2001
From: Alexandre Dufour <>
Date: Mon, 17 Sep 2018 21:07:40 +0200
Subject: [PATCH] QuantityDimension: Fixed an issue where dividing by a powered
 or product dimension would return a non-canonical dimension

---
 .../indriya/quantity/QuantityDimension.java   |  5 +++--
 .../quantity/QuantityDimensionTest.java       | 22 +++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/src/main/java/tech/units/indriya/quantity/QuantityDimension.java b/src/main/java/tech/units/indriya/quantity/QuantityDimension.java
index 37c192fe..c675a72d 100644
--- a/src/main/java/tech/units/indriya/quantity/QuantityDimension.java
+++ b/src/main/java/tech/units/indriya/quantity/QuantityDimension.java
@@ -35,6 +35,7 @@
 
 import tech.units.indriya.AbstractUnit;
 import tech.units.indriya.unit.BaseUnit;
+import tech.units.indriya.unit.ProductUnit;
 import tech.units.indriya.unit.Units;
 
 import java.io.Serializable;
@@ -220,7 +221,7 @@ public QuantityDimension multiply(QuantityDimension that) {
    * @since 1.0
    */
   public Dimension divide(Dimension that) {
-    return this.multiply(that.pow(-1));
+      return that instanceof QuantityDimension ? this.divide((QuantityDimension) that) : this.divide(that);
   }
 
   /**
@@ -232,7 +233,7 @@ public Dimension divide(Dimension that) {
    * @since 1.0
    */
   public QuantityDimension divide(QuantityDimension that) {
-    return this.multiply(that.pow(-1));
+    return new QuantityDimension(ProductUnit.ofQuotient(pseudoUnit, that.pseudoUnit));
   }
 
   /**
diff --git a/src/test/java/tech/units/indriya/quantity/QuantityDimensionTest.java b/src/test/java/tech/units/indriya/quantity/QuantityDimensionTest.java
index 8f1eb994..8db9a0c0 100644
--- a/src/test/java/tech/units/indriya/quantity/QuantityDimensionTest.java
+++ b/src/test/java/tech/units/indriya/quantity/QuantityDimensionTest.java
@@ -95,6 +95,28 @@ public void divisionIsDoneCorrectlyInOverloadedQuantityDimensionMethod() {
     assertEquals("[L]/[M]", result.toString());
   }
 
+  /**
+   * Verifies that the division is done correctly on powered units. Relies on the toString method to
+   * verify the result.
+   */
+  @Test
+  public void divisionIsDoneCorrectlyOnPoweredBaseUnits() {
+    Dimension m2 = QuantityDimension.MASS.pow(2);
+    Dimension result = QuantityDimension.LENGTH.divide(m2);
+    assertEquals("[L]/[M]²", result.toString());
+  }
+
+  /**
+   * Verifies that the division is done correctly on powered units. Relies on the toString method to
+   * verify the result.
+   */
+  @Test
+  public void divisionIsDoneCorrectlyOnPoweredProductUnits() {
+    Dimension ml = QuantityDimension.MASS.multiply(QuantityDimension.LENGTH);
+    Dimension result = QuantityDimension.LENGTH.divide(ml);
+    assertEquals("1/[M]", result.toString());
+  }
+
   /**
    * Verifies that raising to a power is done correctly by checking that multiplication with itself is the same as raising to the power of two.
    */