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Log.javaAPI DocApache Poi 3.0.13127Sun Mar 11 12:59:30 GMT 2007org.apache.poi.hssf.record.formula.functions

Log.java

/*
* 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.
*/
/*
 * Created on May 6, 2005
 *
 */
package org.apache.poi.hssf.record.formula.functions;

import org.apache.poi.hssf.record.formula.eval.BlankEval;
import org.apache.poi.hssf.record.formula.eval.ErrorEval;
import org.apache.poi.hssf.record.formula.eval.Eval;
import org.apache.poi.hssf.record.formula.eval.NumberEval;
import org.apache.poi.hssf.record.formula.eval.NumericValueEval;
import org.apache.poi.hssf.record.formula.eval.ValueEval;
import org.apache.poi.hssf.record.formula.eval.ValueEvalToNumericXlator;

/**
 * @author Amol S. Deshmukh < amolweb at ya hoo dot com >
 * Log: LOG(number,[base])
 */
public class Log extends NumericFunction {

    private static final double DEFAULT_BASE = 10;

    public Eval evaluate(Eval[] operands, int srcRow, short srcCol) {
        double d = 0;
        double base = DEFAULT_BASE;
        double num = 0;
        ValueEval retval = null;

        switch (operands.length) {
        default:
            retval = ErrorEval.VALUE_INVALID;
            break;
        case 2: // second arg is base
            ValueEval ve = singleOperandEvaluate(operands[1], srcRow, srcCol);
            if (ve instanceof NumericValueEval) {
                NumericValueEval ne = (NumericValueEval) ve;
                base = ne.getNumberValue();
            }
            else if (ve instanceof BlankEval) {
                // do nothing
            }
            else {
                retval = ErrorEval.NUM_ERROR;
            }

        case 1: // first arg is number
            if (retval == null) {
                ValueEval vev = singleOperandEvaluate(operands[0], srcRow, srcCol);
                if (vev instanceof NumericValueEval) {
                    NumericValueEval ne = (NumericValueEval) vev;
                    num = ne.getNumberValue();
                }
                else if (vev instanceof BlankEval) {
                    // do nothing
                }
                else {
                    retval = ErrorEval.NUM_ERROR;
                }
            }
        }

        if (retval == null) {
            d = (base == E)
                ? Math.log(num)
                : Math.log(num) / Math.log(base);
            retval = (Double.isNaN(d) || Double.isInfinite(d)) ? (ValueEval) ErrorEval.VALUE_INVALID : new NumberEval(d);
        }
        return retval;
    }

}