Fix root-node precision problems

tzaeschke · Jun 30, 2024 · f55e4b8 · f55e4b8
1 parent 9c04601
commit f55e4b8
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Showing 3 changed files with 24 additions and 10 deletions.
diff --git a/src/main/java/org/tinspin/index/qthypercube2/QuadTreeKD2.java b/src/main/java/org/tinspin/index/qthypercube2/QuadTreeKD2.java
@@ -128,9 +128,9 @@ private void adjustRootSize(double[] key) {
 			return;
 		}
 		if (root.getRadius() == INITIAL_RADIUS) {
-			double dMax = maxOrthoDistance(key, root.getCenter());
+			double dMax = MathTools.maxDelta(key, root.getCenter());
 			for (int i = 0; i < root.getValueCount(); i++) {
-				dMax = Math.max(dMax, maxOrthoDistance(root.getValues()[i].point(), root.getCenter()));
+				dMax = Math.max(dMax, MathTools.maxDelta(root.getValues()[i].point(), root.getCenter()));
 			}
 			double radius = MathTools.floorPowerOfTwo(dMax) * 2;
 			if (radius > 0) {
@@ -142,14 +142,6 @@ private void adjustRootSize(double[] key) {
 		}
 	}
 
-	private static double maxOrthoDistance(double[] v1, double[] v2) {
-		double dMax = 0;
-		for (int i = 0; i < v1.length; i++) {
-			dMax = Math.max(dMax, Math.abs(v1[i] - v2[i]));
-		}
-		return dMax;
-	}
-
 	/**
 	 * Check whether a given key exists.
 	 * @param key the key to check

diff --git a/src/main/java/org/tinspin/index/util/MathTools.java b/src/main/java/org/tinspin/index/util/MathTools.java
@@ -45,4 +45,18 @@ public static double[] floorPowerOfTwoCopy(double[] d) {
         }
         return d2;
     }
+
+    /**
+     * Returns the maximal delta between any pair of scalars in the vector.
+     * @param v1 vector 1
+     * @param v2 vector 2
+     * @return maximal delta (always >= 0).
+     */
+    public static double maxDelta(double[] v1, double[] v2) {
+        double dMax = 0;
+        for (int i = 0; i < v1.length; i++) {
+            dMax = Math.max(dMax, Math.abs(v1[i] - v2[i]));
+        }
+        return dMax;
+    }
 }
diff --git a/src/test/java/org/tinspin/util/MathToolsTest.java b/src/test/java/org/tinspin/util/MathToolsTest.java
@@ -45,4 +45,12 @@ public void powerOfTwoFloor_vector() {
         assertEquals(16, dCopy[3], 0.0);
         assertEquals(256, dCopy[4], 0.0);
     }
+
+    @Test
+    public void maxDelta() {
+        assertEquals(12, MathTools.maxDelta(new double[]{-4.}, new double[]{8.}), 0.0);
+        assertEquals(12, MathTools.maxDelta(new double[]{8.}, new double[]{-4.}), 0.0);
+
+        assertEquals(4, MathTools.maxDelta(new double[]{2, 4, 2}, new double[]{3, 8, 4}), 0.0);
+    }
 }