Increase unit vector delta for bfloat16 tests (elastic#136602)

Author: thecoop

muted-tests.yml

@@ -618,9 +618,6 @@ tests:
 - class: org.elasticsearch.xpack.remotecluster.CrossClusterEsqlRCS2UnavailableRemotesIT
   method: testEsqlRcs2UnavailableRemoteScenarios
   issue: https://github.com/elastic/elasticsearch/issues/136493
-- class: org.elasticsearch.index.codec.vectors.es93.ES93HnswBinaryQuantizedBFloat16VectorsFormatTests
-  method: testFloatVectorScorerIteration
-  issue: https://github.com/elastic/elasticsearch/issues/136566
 
 # Examples:
 #

server/src/main/java/org/elasticsearch/index/codec/vectors/BQVectorUtils.java

@@ -27,7 +27,7 @@
 /** Utility class for vector quantization calculations */
 public class BQVectorUtils {
     // NOTE: this is currently > 1e-4f due to bfloat16
-    private static final float EPSILON = 1e-2f;
+    private static final float EPSILON = 0.02f;
 
     public static double sqrtNewtonRaphson(double x, double curr, double prev) {
         return (curr == prev) ? curr : sqrtNewtonRaphson(x, 0.5 * (curr + x / curr), curr);