/*
* 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.pig.piggybank.evaluation.math;
import java.io.IOException;
import java.util.List;
import java.util.ArrayList;
import org.apache.pig.EvalFunc;
import org.apache.pig.FuncSpec;
import org.apache.pig.data.Tuple;
import org.apache.pig.impl.logicalLayer.schema.Schema;
import org.apache.pig.data.DataType;
import org.apache.pig.impl.logicalLayer.FrontendException;
/**
* math.ULP implements a binding to the Java function
* {@link java.lang.Math#ulp(float) Math.ulp(float)}.
* Given a single data atom it Returns the size of an ulp
* of the argument.
*
* <dl>
* <dt><b>Parameters:</b></dt>
* <dd><code>value</code> - <code>Float</code>.</dd>
*
* <dt><b>Return Value:</b></dt>
* <dd><code>Float</code> </dd>
*
* <dt><b>Return Schema:</b></dt>
* <dd>ULP_inputSchema</dd>
*
* <dt><b>Example:</b></dt>
* <dd><code>
* register math.jar;<br/>
* A = load 'mydata' using PigStorage() as ( float1 );<br/>
* B = foreach A generate float1, math.ULP(float1);
* </code></dd>
* </dl>
*
* @see Math#ulp(float)
* @see
* @author ajay garg
*
*/
public class FloatUlp extends EvalFunc<Float>{
/**
* java level API
* @param input expects a single numeric value
* @param output returns a single numeric value,
* the size of an ulp of the argument.
*/
public Float exec(Tuple input) throws IOException {
if (input == null || input.size() == 0 || input.get(0) == null)
return null;
try{
Float d = (Float)input.get(0);
return Math.ulp(d);
} catch(Exception e){
throw new IOException("Caught exception in DoubleUlp", e);
}
}
@Override
public Schema outputSchema(Schema input) {
return new Schema(new Schema.FieldSchema(getSchemaName(this.getClass().getName().toLowerCase(), input), DataType.FLOAT));
}
}