4 files changed, 37 insertions, 19 deletions
diff --git a/src/main/java/sevenUnits/unit/LinearUnit.java b/src/main/java/sevenUnits/unit/LinearUnit.java
index 3c3703c..d453a43 100644
--- a/src/main/java/sevenUnits/unit/LinearUnit.java
+++ b/src/main/java/sevenUnits/unit/LinearUnit.java
@@ -227,6 +227,19 @@ public final class LinearUnit extends Unit {
 			return false;
 		final LinearUnit other = (LinearUnit) obj;
 		return Objects.equals(this.getBase(), other.getBase())
+				&& Double.compare(this.getConversionFactor(),
+						other.getConversionFactor()) == 0;
+	}
+
+	/**
+	 * @return true iff this unit and other are equal,
+	 * ignoring small differences caused by floating-point error.
+	 * 
+	 * @apiNote This method is not transitive,
+	 * so it cannot be used as an equals method.
+	 */
+	public boolean equalsApproximately(final LinearUnit other) {
+		return Objects.equals(this.getBase(), other.getBase())
 				&& DecimalComparison.equals(this.getConversionFactor(),
 						other.getConversionFactor());
 	}
@@ -247,7 +260,7 @@ public final class LinearUnit extends Unit {
 	@Override
 	public int hashCode() {
 		return 31 * this.getBase().hashCode()
-				+ DecimalComparison.hash(this.getConversionFactor());
+				+ Double.hashCode(this.getConversionFactor());
 	}
 	
 	/**
diff --git a/src/main/java/sevenUnits/unit/UnitPrefix.java b/src/main/java/sevenUnits/unit/UnitPrefix.java
index 9035969..ec4be48 100644
--- a/src/main/java/sevenUnits/unit/UnitPrefix.java
+++ b/src/main/java/sevenUnits/unit/UnitPrefix.java
@@ -119,6 +119,22 @@ public final class UnitPrefix implements Nameable {
 		if (!(obj instanceof UnitPrefix))
 			return false;
 		final UnitPrefix other = (UnitPrefix) obj;
+		return Double.compare(this.getMultiplier(),
+				other.getMultiplier()) == 0;
+	}
+
+	/**
+	 * @return true iff this prefix and other are equal,
+	 * ignoring small differences caused by floating-point error.
+	 * 
+	 * @apiNote This method is not transitive,
+	 * so it cannot be used as an equals method.
+	 */
+	public boolean equalsApproximately(final UnitPrefix other) {
+		if (this == other)
+			return true;
+		if (other == null)
+			return false;
 		return DecimalComparison.equals(this.getMultiplier(),
 				other.getMultiplier());
 	}
@@ -143,7 +159,7 @@ public final class UnitPrefix implements Nameable {
 	 */
 	@Override
 	public int hashCode() {
-		return DecimalComparison.hash(this.getMultiplier());
+		return Double.hashCode(this.getMultiplier());
 	}
 
 	/**
diff --git a/src/main/java/sevenUnits/utils/DecimalComparison.java b/src/main/java/sevenUnits/utils/DecimalComparison.java
index 62c3720..03dd15b 100644
--- a/src/main/java/sevenUnits/utils/DecimalComparison.java
+++ b/src/main/java/sevenUnits/utils/DecimalComparison.java
@@ -69,7 +69,6 @@ public final class DecimalComparison {
 	 * @return whether they are equal
 	 * @since 2019-03-18
 	 * @since v0.2.0
-	 * @see #hash(double)
 	 */
 	public static final boolean equals(final double a, final double b) {
 		return DecimalComparison.equals(a, b, DOUBLE_EPSILON);
@@ -194,7 +193,6 @@ public final class DecimalComparison {
 	 * @param b second value to test
 	 * @return whether they are equal
 	 * @since 2020-09-07
-	 * @see #hash(double)
 	 */
 	public static final boolean equals(final UncertainDouble a,
 			final UncertainDouble b) {
@@ -236,19 +234,6 @@ public final class DecimalComparison {
 						epsilon);
 	}
 
-	/**
-	 * Takes the hash code of doubles. Values that are equal according to
-	 * {@link #equals(double, double)} will probably have the same hash code.
-	 * 
-	 * @param d double to hash
-	 * @return hash code of double
-	 * @since 2019-10-16
-	 */
-	// TODO reconsider using this
-	public static final int hash(final double d) {
-		return Float.hashCode((float) d);
-	}
-
 	// You may NOT get any DecimalComparison instances
 	private DecimalComparison() {
 		throw new AssertionError();
diff --git a/src/test/java/sevenUnits/unit/UnitTest.java b/src/test/java/sevenUnits/unit/UnitTest.java
index 6ac0ebd..f8d3040 100644
--- a/src/test/java/sevenUnits/unit/UnitTest.java
+++ b/src/test/java/sevenUnits/unit/UnitTest.java
@@ -48,8 +48,12 @@ class UnitTest {
 		final LinearUnit foot = Metric.METRE.times(0.3048)
 				.withName(NameSymbol.of("foot", "ft"));
 		
-		assertEquals(inch.plus(foot), Metric.METRE.times(0.3302));
-		assertEquals(foot.minus(inch), Metric.METRE.times(0.2794));
+		assertTrue(inch.plus(foot).equalsApproximately(Metric.METRE.times(0.3302)),
+				String.format("Expected: %s, Actual: %s",
+						inch.plus(foot), Metric.METRE.times(0.3302)));
+		assertTrue(foot.minus(inch).equalsApproximately(Metric.METRE.times(0.2794)),
+				String.format("Expected: %s, Actual: %s",
+						foot.minus(inch), Metric.METRE.times(0.2794)));
 		
 		// test with LinearUnitValue
 		final LinearUnitValue value1 = LinearUnitValue.getExact(Metric.METRE, 15);