real.java

利用开源的源码为一个朋友的V3手机手机写的科学计算器

package xcalc;

/**
 * <b>Java integer implementation of 63-bit precision floating point.</b>
 * <br><i>Version 1.09</i>
 *
 * <p>Copyright 2003-2006 Roar Lauritzsen <[e-mail]>
 *
 * <blockquote>
 * <p>This library 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.
 *
 * <p>This library 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.
 *
 * <p>The following link provides a copy of the GNU General Public License:
 * <br>&nbsp;&nbsp;&nbsp;&nbsp;<a
 * href="http://www.gnu.org/licenses/gpl.txt">http://www.gnu.org/licenses/gpl.txt</a>
 * <br>If you are unable to obtain the copy from this address, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307 USA
 * </blockquote>
 *
 * <p><b>General notes</b>
 * <ul>
 *
 *   <li><code>Real</code> objects are not immutable, like Java
 *   <code>Double</code> or <code>BigDecimal</code>. This means that
 *   you should not think of a <code>Real</code> object as a "number",
 *   but rather as a "register holding a number". This design choice
 *   is done to encourage object reuse and limit garbage production
 *   for more efficient execution on e.g. a limited MIDP device. The
 *   design choice is reflected in the API, where an operation like
 *   {@link #add(Real) add} does not return a new object containing
 *   the result (as with {@link
 *   java.math.BigDecimal#add(java.math.BigDecimal) BigDecimal}), but
 *   rather adds the argument to the object itself, and returns
 *   nothing.
 *
 *   <li>This library implements infinities and NaN (Not-a-Number)
 *   following the IEEE 754 logic. If an operation produces a result
 *   larger (in magnitude) than the largest representable number, a
 *   value representing positive or negative infinity is generated. If
 *   an operation produces a result smaller than the smallest
 *   representable number, a positive or negative zero is
 *   generated. If an operation is undefined, a NaN value is
 *   produced. Abnormal numbers are often fine to use in further
 *   calculations. In most cases where the final result would be
 *   meaningful, abnormal numbers accomplish this,
 *   e.g. atan(1/0)=&pi;/2. In most cases where the final result is
 *   not meaningful, a NaN will be produced.
 *
 *   <li>Error bounds listed under <a href="#method_detail">Method
 *   Detail</a> are calculated using William Rossi's <a
 *   href="http://dfp.sourceforge.net/">rossi.dfp.dfp</a> at 40
 *   decimal digits accuracy. Error bounds may increase when results
 *   approach zero or infinity. The abbreviation {@link
 *   Math#ulp(double) ULP} means Unit in the Last Place. An error
 *   bound of 锟