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/tags/release-0.0.0-rc0/hive/external/ql/src/java/org/apache/hadoop/hive/ql/udf/UDFSqrt.java

#
Java | 52 lines | 23 code | 6 blank | 23 comment | 5 complexity | b02758366dca04f0e52e585d00322c0d MD5 | raw file
 1/**
 2 * Licensed to the Apache Software Foundation (ASF) under one
 3 * or more contributor license agreements.  See the NOTICE file
 4 * distributed with this work for additional information
 5 * regarding copyright ownership.  The ASF licenses this file
 6 * to you under the Apache License, Version 2.0 (the
 7 * "License"); you may not use this file except in compliance
 8 * with the License.  You may obtain a copy of the License at
 9 *
10 *     http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18
19package org.apache.hadoop.hive.ql.udf;
20
21import org.apache.hadoop.hive.ql.exec.Description;
22import org.apache.hadoop.hive.ql.exec.UDF;
23import org.apache.hadoop.hive.serde2.io.DoubleWritable;
24
25/**
26 * Implementation of the SQRT UDF found in many databases.
27 */
28@Description(name = "sqrt",
29    value = "_FUNC_(x) - returns the square root of x",
30    extended = "Example:\n "
31    + "  > SELECT _FUNC_(4) FROM src LIMIT 1;\n" + "  2")
32public class UDFSqrt extends UDF {
33  private DoubleWritable result = new DoubleWritable();
34
35  public UDFSqrt() {
36  }
37
38  /**
39   * Return NULL for NULL or negative inputs; otherwise, return the square root.
40   */
41  public DoubleWritable evaluate(DoubleWritable i) {
42    if (i == null) {
43      return null;
44    } else if (i.get() < 0) {
45      return null;
46    } else {
47      result.set(Math.sqrt(i.get()));
48      return result;
49    }
50  }
51
52}