strictmath.java

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/*
 * @(#)StrictMath.java	1.18 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program 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 version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package java.lang;
import java.util.Random;


/**
 * The class <code>StrictMath</code> contains methods for performing basic 
 * numeric operations such as the elementary exponential, logarithm, 
 * square root, and trigonometric functions. 
 * <p>
 * To help ensure portability of Java programs, the definitions of 
 * many of the numeric functions in this package require that they 
 * produce the same results as certain published algorithms. These 
 * algorithms are available from the well-known network library 
 * <code>netlib</code> as the package "Freely Distributable 
 * Math Library" (<code>fdlibm</code>). These algorithms, which 
 * are written in the C programming language, are then to be 
 * understood as executed with all floating-point operations 
 * following the rules of Java floating-point arithmetic. 
 * <p>
 * The network library may be found on the World Wide Web at:
 * <blockquote><pre>
 *   <a href="http://metalab.unc.edu/">http://metalab.unc.edu/</a>
 * </pre></blockquote>
 * <p>
 * The Java math library is defined with respect to the version of 
 * <code>fdlibm</code> dated January 4, 1995. Where 
 * <code>fdlibm</code> provides more than one definition for a 
 * function (such as <code>acos</code>), use the "IEEE 754 core 
 * function" version (residing in a file whose name begins with 
 * the letter <code>e</code>). 
 *
 * @author  unascribed
 * @version 1.9, 02/02/00
 * @since   1.3
 */

public final strictfp class StrictMath {

    /* Work-around for Symbian tool bug.  No longer needed. */
    private static native void init();
    static {
	init();
    }

    /**
     * Don't let anyone instantiate this class.
     */
    private StrictMath() {}

    /**
     * The <code>double</code> value that is closer than any other to
     * <i>e</i>, the base of the natural logarithms.
     */
    public static final double E = 2.7182818284590452354;

    /**
     * The <code>double</code> value that is closer than any other to
     * <i>pi</i>, the ratio of the circumference of a circle to its
     * diameter.
     */
    public static final double PI = 3.14159265358979323846;

    /**
     * Returns the trigonometric sine of an angle. Special cases:
     * <ul><li>If the argument is NaN or an infinity, then the 
     * result is NaN.
     * <li>If the argument is zero, then the result is a zero with the
     * same sign as the argument.</ul>
     *
     * @param   a   an angle, in radians.
     * @return  the sine of the argument.
     */
    public static native double sin(double a);
    
    /**
     * Returns the trigonometric cosine of an angle. Special cases:
     * <ul><li>If the argument is NaN or an infinity, then the 
     * result is NaN.</ul>
     *
     * @param   a   an angle, in radians.
     * @return  the cosine of the argument.
     */
    public static native double cos(double a);
   
    /**
     * Returns the trigonometric tangent of an angle. Special cases:
     * <ul><li>If the argument is NaN or an infinity, then the result 
     * is NaN.
     * <li>If the argument is zero, then the result is a zero with the
     * same sign as the argument.</ul>
     *
     * @param   a   an angle, in radians.
     * @return  the tangent of the argument.
     */
    public static native double tan(double a);

    /**
     * Returns the arc sine of an angle, in the range of -<i>pi</i>/2 through
     * <i>pi</i>/2. Special cases: 
     * <ul><li>If the argument is NaN or its absolute value is greater 
     * than 1, then the result is NaN.
     * <li>If the argument is zero, then the result is a zero with the
     * same sign as the argument.</ul>
     *
     * @param   a   the value whose arc sine is to be returned.
     * @return  the arc sine of the argument.
     */
    public static native double asin(double a);

    /**
     * Returns the arc cosine of an angle, in the range of 0.0 through
     * <i>pi</i>. Special case:
     * <ul><li>If the argument is NaN or its absolute value is greater 
     * than 1, then the result is NaN.</ul>
     *
     * @param   a   the value whose arc cosine is to be returned.
     * @return  the arc cosine of the argument.
     */
    public static native double acos(double a); 

    /**
     * Returns the arc tangent of an angle, in the range of -<i>pi</i>/2
     * through <i>pi</i>/2. Special cases: 
     * <ul><li>If the argument is NaN, then the result is NaN.
     * <li>If the argument is zero, then the result is a zero with the
     * same sign as the argument.</ul>
     *
     * @param   a   the value whose arc tangent is to be returned.
     * @return  the arc tangent of the argument.
     */
    public static native double atan(double a);

    /**
     * Converts an angle measured in degrees to an approximately
     * equivalent angle measured in radians.  The conversion from
     * degrees to radians is generally inexact.
     *
     * @param   angdeg   an angle, in degrees
     * @return  the measurement of the angle <code>angdeg</code>
     *          in radians.
     */
    public static double toRadians(double angdeg) {
	return angdeg / 180.0 * PI;
    }

    /**
     * Converts an angle measured in radians to an approximately
     * equivalent angle measured in degrees.  The conversion from
     * radians to degrees is generally inexact; users should
     * <i>not</i> expect <code>cos(toRadians(90.0))</code> to exactly
     * equal <code>0.0</code>.
     *
     * @param   angrad   an angle, in radians
     * @return  the measurement of the angle <code>angrad</code>
     *          in degrees.
     */
    public static double toDegrees(double angrad) {
	return angrad * 180.0 / PI;
    }

    /**
     * Returns Euler's number <i>e</i> raised to the power of a
     * <code>double</code> value. Special cases:
     * <ul><li>If the argument is NaN, the result is NaN.
     * <li>If the argument is positive infinity, then the result is 
     * positive infinity.
     * <li>If the argument is negative infinity, then the result is 
     * positive zero.</ul>
     *
     * @param   a   the exponent to raise <i>e</i> to.
     * @return  the value <i>e</i><sup><code>a</code></sup>, 
     *		where <i>e</i> is the base of the natural logarithms.
     */
    public static native double exp(double a);

    /**
     * Returns the natural logarithm (base <i>e</i>) of a <code>double</code>
     * value. Special cases:
     * <ul><li>If the argument is NaN or less than zero, then the result 
     * is NaN.
     * <li>If the argument is positive infinity, then the result is 
     * positive infinity.
     * <li>If the argument is positive zero or negative zero, then the 
     * result is negative infinity.</ul>
     *
     * @param   a   a number greater than <code>0.0</code>.
     * @return  the value ln&nbsp;<code>a</code>, the natural logarithm of
     *          <code>a</code>.
     */
    public static native double log(double a);

    /**
     * Returns the correctly rounded positive square root of a
     * <code>double</code> value.
     * Special cases:
     * <ul><li>If the argument is NaN or less than zero, then the result 
     * is NaN. 
     * <li>If the argument is positive infinity, then the result is positive 
     * infinity. 
     * <li>If the argument is positive zero or negative zero, then the 
     * result is the same as the argument.</ul>
     * Otherwise, the result is the <code>double</code> value closest to 
     * the true mathematical square root of the argument value.
     *
     * @param   a   a value.
     * <!--@return  the value of &radic;&nbsp;<code>a</code>.-->
     * @return  the positive square root of <code>a</code>.
     */
    public static native double sqrt(double a);

    /**
     * Computes the remainder operation on two arguments as prescribed 
     * by the IEEE 754 standard.
     * The remainder value is mathematically equal to 
     * <code>f1&nbsp;-&nbsp;f2</code>&nbsp;&times;&nbsp;<i>n</i>,
     * where <i>n</i> is the mathematical integer closest to the exact 
     * mathematical value of the quotient <code>f1/f2</code>, and if two 
     * mathematical integers are equally close to <code>f1/f2</code>, 
     * then <i>n</i> is the integer that is even. If the remainder is 
     * zero, its sign is the same as the sign of the first argument. 
     * Special cases:
     * <ul><li>If either argument is NaN, or the first argument is infinite, 
     * or the second argument is positive zero or negative zero, then the 
     * result is NaN.
     * <li>If the first argument is finite and the second argument is 
     * infinite, then the result is the same as the first argument.</ul>
     *
     * @param   f1   the dividend.
     * @param   f2   the divisor.
     * @return  the remainder when <code>f1</code> is divided by
     *          <code>f2</code>.
     */
    public static native double IEEEremainder(double f1, double f2);

    /**
     * Returns the smallest (closest to negative infinity) 
     * <code>double</code> value that is not less than the argument and is 
     * equal to a mathematical integer. Special cases:
     * <ul><li>If the argument value is already equal to a mathematical 
     * integer, then the result is the same as the argument. 
     * <li>If the argument is NaN or an infinity or positive zero or negative 
     * zero, then the result is the same as the argument.