| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.solr.util.hll; |
| |
| import org.apache.lucene.util.LuceneTestCase; |
| import org.junit.Test; |
| |
| /** |
| * Tests {@link HLLUtil} static methods. |
| */ |
| public class HLLUtilTest extends LuceneTestCase { |
| /** |
| * Tests that {@link HLLUtil#largeEstimatorCutoff(int, int)} is the same |
| * as a trivial implementation. |
| */ |
| @Test |
| public void largeEstimatorCutoffTest() { |
| for(int log2m=HLL.MINIMUM_LOG2M_PARAM; log2m<=HLL.MAXIMUM_LOG2M_PARAM; log2m++) { |
| for(int regWidth=HLL.MINIMUM_REGWIDTH_PARAM; regWidth<=HLL.MINIMUM_REGWIDTH_PARAM; regWidth++) { |
| final double cutoff = HLLUtil.largeEstimatorCutoff(log2m, regWidth); |
| |
| // See blog post (http://research.neustar.biz/2013/01/24/hyperloglog-googles-take-on-engineering-hll/) |
| // and original paper (Fig. 3) for information on 2^L and |
| // "large range correction" cutoff. |
| final double expected = Math.pow(2, Math.pow(2, regWidth) - 2 + log2m) / 30.0; |
| assertEquals(cutoff, expected, 0.0001); |
| } |
| } |
| } |
| } |