extremely simple version natural logarithm, using no algorithm tricks, but just via doubles and recreating BigDecimal Might give less accurate results, but this is to be tested. - Java java.math

Java examples for java.math:BigDecimal Trigonometric Function

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Description

extremely simple version natural logarithm, using no algorithm tricks, but just via doubles and recreating BigDecimal Might give less accurate results, but this is to be tested.

Demo Code

/*/* w  w w . j ava  2  s.  c  o  m*/
 Anders H?fft, note: This class was downloaded as a quick, and temprory, way of getting a BigDecimal ln() method. 
 The code belongs to Cyclos. See comment below:

 This file is part of Cyclos (www.cyclos.org).
 A project of the Social Trade Organisation (www.socialtrade.org).
 Cyclos is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.
 Cyclos is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 GNU General Public License for more details.
 You should have received a copy of the GNU General Public License
 along with Cyclos; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
//package com.java2s;
import java.math.BigDecimal;

import java.math.MathContext;

public class Main {
    public static void main(String[] argv) throws Exception {
        BigDecimal x = new BigDecimal("1234");
        int scale = 2;
        System.out.println(simpleLn(x, scale));
    }

    /**
     * extremely simple version natural logarithm, using no algorithm tricks, but just via doubles and recreating BigDecimal Might give less accurate
     * results, but this is to be tested. As long as this hasn't happened it is deprecated.
     */
    @Deprecated
    public static BigDecimal simpleLn(final BigDecimal x, final int scale) {
        final long unscaledValue = x.unscaledValue().longValue();
        final int scalevalue = x.scale();
        final double result = Math.log(unscaledValue)
                - (scalevalue * Math.log(10.0));
        return new BigDecimal(result, new MathContext(scale));
    }
}

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