poi/src/main/java/org/apache/poi/ss/formula/atp/MRound.java

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   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
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       http://www.apache.org/licenses/LICENSE-2.0

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   distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.poi.ss.formula.atp;

import org.apache.poi.ss.formula.OperationEvaluationContext;
import org.apache.poi.ss.formula.eval.*;
import org.apache.poi.ss.formula.functions.FreeRefFunction;
import org.apache.poi.ss.formula.functions.NumericFunction;

/**
 * Implementation of Excel 'Analysis ToolPak' function MROUND()<br>
 *
 * Returns a number rounded to the desired multiple.<p>
 *
 * <b>Syntax</b><br>
 * <b>MROUND</b>(<b>number</b>, <b>multiple</b>)
 */
final class MRound implements FreeRefFunction {

	public static final FreeRefFunction instance = new MRound();

	private MRound() {
		// enforce singleton
	}

	public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
        double number, multiple, result;

        if (args.length != 2) {
            return ErrorEval.VALUE_INVALID;
        }

        try {
            number = OperandResolver.coerceValueToDouble(OperandResolver.getSingleValue(args[0], ec.getRowIndex(), ec.getColumnIndex()));
            multiple = OperandResolver.coerceValueToDouble(OperandResolver.getSingleValue(args[1], ec.getRowIndex(), ec.getColumnIndex()));

            if( multiple == 0.0 ) {
                result = 0.0;
            } else {
                if(number*multiple < 0) {
                    // Returns #NUM! because the number and the multiple have different signs
                    throw new EvaluationException(ErrorEval.NUM_ERROR);
                }
                result = multiple * Math.round( number / multiple );
            }
            NumericFunction.checkValue(result);
            return new NumberEval(result);
        } catch (EvaluationException e) {
            return e.getErrorEval();
        }
	}
}