www.pudn.com > j2me_cldc-1_1-fcs-src-winunix.rar > Math.java

/*
 * Copyright © 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 */

package java.lang;

/**
 * The class Math contains methods for performing basic
 * numeric operations.
 *
 * @author  unascribed
 * @version 12/17/01 (CLDC 1.1)
 * @since   JDK1.0, CLDC 1.0
 */

public final strictfp class Math {

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

    /**
     * The double value that is closer than any other to
     * e, the base of the natural logarithms.
     * @since CLDC 1.1
     */
    public static final double E = 2.7182818284590452354;

    /**
     * The double value that is closer than any other to
     * pi, the ratio of the circumference of a circle to its diameter.
     * @since CLDC 1.1
     */
    public static final double PI = 3.14159265358979323846;

    /**
     * Returns the trigonometric sine of an angle.  Special cases:
     * 
If the argument is NaN or an infinity, then the 
     * result is NaN.
     * 
If the argument is positive zero, then the result is 
     * positive zero; if the argument is negative zero, then the 
     * result is negative zero.
     *
     * @param   a   an angle, in radians.
     * @return  the sine of the argument.
     * @since   CLDC 1.1
     */
    public static native double sin(double a); 

    /**
     * Returns the trigonometric cosine of an angle. Special case:
     * 
If the argument is NaN or an infinity, then the 
     * result is NaN.
     *
     * @param   a   an angle, in radians.
     * @return  the cosine of the argument.
     * @since   CLDC 1.1
     */
    public static native double cos(double a); 

    /**
     * Returns the trigonometric tangent of an angle.  Special cases:
     * 
If the argument is NaN or an infinity, then the result 
     * is NaN.
     * 
If the argument is positive zero, then the result is 
     * positive zero; if the argument is negative zero, then the 
     * result is negative zero
     *
     * @param   a   an angle, in radians.
     * @return  the tangent of the argument.
     * @since   CLDC 1.1
     */
    public static native double tan(double a);

    /**
     * Converts an angle measured in degrees to the equivalent angle
     * measured in radians.
     *
     * @param   angdeg   an angle, in degrees
     * @return  the measurement of the angle angdeg
     *          in radians.
     * @since   CLDC 1.1
     */
    public static double toRadians(double angdeg) {
        return angdeg / 180.0 * PI;
    }

    /**
     * Converts an angle measured in radians to the equivalent angle
     * measured in degrees.
     *
     * @param   angrad   an angle, in radians
     * @return  the measurement of the angle angrad
     *          in degrees.
     * @since   CLDC 1.1
     */
    public static double toDegrees(double angrad) {
        return angrad * 180.0 / PI;
    }

    /**
     * Returns the correctly rounded positive square root of a 
     * double value.
     * Special cases:
     * 
If the argument is NaN or less than zero, then the result 
     * is NaN. 
     * 
If the argument is positive infinity, then the result is positive 
     * infinity. 
     * 
If the argument is positive zero or negative zero, then the 
     * result is the same as the argument.
     * 
     * @param   a   a double value.
     * @return  the positive square root of a.
     *          If the argument is NaN or less than zero, the result is NaN.
     * @since   CLDC 1.1
     */
    public static native double sqrt(double a);

    /**
     * Returns the smallest (closest to negative infinity)
     * double value that is not less than the argument and is
     * equal to a mathematical integer. Special cases:
     * 
If the argument value is already equal to a mathematical
     * integer, then the result is the same as the argument.
     * 
If the argument is NaN or an infinity or positive zero or negative
     * zero, then the result is the same as the argument.
     * 
If the argument value is less than zero but greater than -1.0,
     * then the result is negative zero.
     * Note that the value of Math.ceil(x) is exactly the
     * value of -Math.floor(-x).
     *
     * @param   a   a double value.
     * 
     * @return  the smallest (closest to negative infinity) 
     *          double value that is not less than the argument
     *          and is equal to a mathematical integer.
     * @since   CLDC 1.1
     */
    public static native double ceil(double a);

    /**
     * Returns the largest (closest to positive infinity)
     * double value that is not greater than the argument and
     * is equal to a mathematical integer. Special cases:
     * 
If the argument value is already equal to a mathematical
     * integer, then the result is the same as the argument.
     * 
If the argument is NaN or an infinity or positive zero or
     * negative zero, then the result is the same as the argument.
     *
     * @param   a   a double value.
     * 
     * @return  the largest (closest to positive infinity)
     *          double value that is not greater than the argument
     *          and is equal to a mathematical integer.
     * @since   CLDC 1.1
     */
    public static native double floor(double a);

    /**
     * Returns the absolute value of an int value.
     * If the argument is not negative, the argument is returned.
     * If the argument is negative, the negation of the argument is returned.
     * 

     * Note that if the argument is equal to the value of
     * Integer.MIN_VALUE, the most negative representable
     * int value, the result is that same value, which is
     * negative.
     *
     * @param   a   an int value.
     * @return  the absolute value of the argument.
     * @see     java.lang.Integer#MIN_VALUE
     */
    public static int abs(int a) {
        return (a < 0) ? -a : a;
    }

    /**
     * Returns the absolute value of a long value.
     * If the argument is not negative, the argument is returned.
     * If the argument is negative, the negation of the argument is returned.
     * 

     * Note that if the argument is equal to the value of
     * Long.MIN_VALUE, the most negative representable
     * long value, the result is that same value, which is
     * negative.
     *
     * @param   a   a long value.
     * @return  the absolute value of the argument.
     * @see     java.lang.Long#MIN_VALUE
     */
    public static long abs(long a) {
        return (a < 0) ? -a : a;
    }

    /**
     * Returns the absolute value of a float value.
     * If the argument is not negative, the argument is returned.
     * If the argument is negative, the negation of the argument is returned.
     * Special cases:
     * 
If the argument is positive zero or negative zero, the
     * result is positive zero.
     * 
If the argument is infinite, the result is positive infinity.
     * 
If the argument is NaN, the result is NaN.
     * In other words, the result is equal to the value of the expression:
     * 
Float.intBitsToFloat(0x7fffffff & Float.floatToIntBits(a))
 
     *
     * @param   a   a float value.
     * @return  the absolute value of the argument.
     * @since   CLDC 1.1
     */
    public static float abs(float a) {
        return (a <= 0.0F) ? 0.0F - a : a;
    }

    /**
     * Returns the absolute value of a double value.
     * If the argument is not negative, the argument is returned.
     * If the argument is negative, the negation of the argument is returned.
     * Special cases:
     * 
If the argument is positive zero or negative zero, the result
     * is positive zero.
     * 
If the argument is infinite, the result is positive infinity.
     * 
If the argument is NaN, the result is NaN.
     * In other words, the result is equal to the value of the expression:
     * 
Double.longBitsToDouble((Double.doubleToLongBits(a)<<1)>>>1)
     *
     * @param   a   a double value.
     * @return  the absolute value of the argument.
     * @since   CLDC 1.1
     */
    public static double abs(double a) {
        return (a <= 0.0D) ? 0.0D - a : a;
    }

    /**
     * Returns the greater of two int values. That is, the
     * result is the argument closer to the value of
     * Integer.MAX_VALUE. If the arguments have the same value,
     * the result is that same value.
     *
     * @param   a   an int value.
     * @param   b   an int value.
     * @return  the larger of a and b.
     * @see     java.lang.Long#MAX_VALUE
     */
    public static int max(int a, int b) {
        return (a >= b) ? a : b;
    }

    /**
     * Returns the greater of two long values. That is, the
     * result is the argument closer to the value of
     * Long.MAX_VALUE. If the arguments have the same value,
     * the result is that same value.
     *
     * @param   a   a long value.
     * @param   b   a long value.
     * @return  the larger of a and b.
     * @see     java.lang.Long#MAX_VALUE
     */
    public static long max(long a, long b) {
        return (a >= b) ? a : b;
    }

    private static long negativeZeroFloatBits = Float.floatToIntBits(-0.0f);
    private static long negativeZeroDoubleBits = Double.doubleToLongBits(-0.0d);

    /**
     * Returns the greater of two float values.  That is, the
     * result is the argument closer to positive infinity. If the
     * arguments have the same value, the result is that same value. If
     * either value is NaN, then the result is NaN. 
     * Unlike the the numerical comparison operators, this method considers
     * negative zero to be strictly smaller than positive zero. If one
     * argument is positive zero and the other negative zero, the result
     * is positive zero.
     *
     * @param   a   a float value.
     * @param   b   a float value.
     * @return  the larger of a and b.
     */
    public static float max(float a, float b) {
        if (a != a) return a; // a is NaN
        if ((a == 0.0f) && (b == 0.0f)
            && (Float.floatToIntBits(a) == negativeZeroFloatBits)) {
            return b;
        }
        return (a >= b) ? a : b;
    }

    /**
     * Returns the greater of two double values.  That is, the
     * result is the argument closer to positive infinity. If the
     * arguments have the same value, the result is that same value. If
     * either value is NaN, then the result is NaN. 
     * Unlike the the numerical comparison operators, this method considers
     * negative zero to be strictly smaller than positive zero. If one
     * argument is positive zero and the other negative zero, the result
     * is positive zero.
     *
     * @param   a   a double value.
     * @param   b   a double value.
     * @return  the larger of a and b.
     */
    public static double max(double a, double b) {
        if (a != a) return a; // a is NaN
        if ((a == 0.0d) && (b == 0.0d)
            && (Double.doubleToLongBits(a) == negativeZeroDoubleBits)) {
            return b;
        }
        return (a >= b) ? a : b;
    }

    /**
     * Returns the smaller of two int values. That is, the
     * result the argument closer to the value of Integer.MIN_VALUE.
     * If the arguments have the same value, the result is that same value.
     *
     * @param   a   an int value.
     * @param   b   an int value.
     * @return  the smaller of a and b.
     * @see     java.lang.Long#MIN_VALUE
     */
    public static int min(int a, int b) {
        return (a <= b) ? a : b;
    }

    /**
     * Returns the smaller of two long values. That is, the
     * result is the argument closer to the value of
     * Long.MIN_VALUE. If the arguments have the same value,
     * the result is that same value.
     *
     * @param   a   a long value.
     * @param   b   a long value.
     * @return  the smaller of a and b.
     * @see     java.lang.Long#MIN_VALUE
     */
    public static long min(long a, long b) {
        return (a <= b) ? a : b;
    }

    /**
     * Returns the smaller of two float values.  That is, the
     * result is the value closer to negative infinity. If the arguments
     * have the same value, the result is that same value. If either value
     * is NaN, then the result is NaN.  Unlike the
     * the numerical comparison operators, this method considers negative zero
     * to be strictly smaller than positive zero.  If one argument is
     * positive zero and the other is negative zero, the result is negative
     * zero.
     *
     * @param   a   a float value.
     * @param   b   a float value.
     * @return  the smaller of a and b.
     * @since   CLDC 1.1
     */
    public static float min(float a, float b) {
        if (a != a) return a; // a is NaN
        if ((a == 0.0f) && (b == 0.0f)
            && (Float.floatToIntBits(b) == negativeZeroFloatBits)) {
            return b;
        }
        return (a <= b) ? a : b;
    }

    /**
     * Returns the smaller of two double values.  That is, the
     * result is the value closer to negative infinity. If the arguments have
     * the same value, the result is that same value. If either value
     * is NaN, then the result is NaN.  Unlike the
     * the numerical comparison operators, this method considers negative zero
     * to be strictly smaller than positive zero. If one argument is
     * positive zero and the other is negative zero, the result is negative
     * zero.
     *
     * @param   a   a double value.
     * @param   b   a double value.
     * @return  the smaller of a and b.
     * @since   CLDC 1.1
     */
    public static double min(double a, double b) {
        if (a != a) return a; // a is NaN
        if ((a == 0.0d) && (b == 0.0d)
            && (Double.doubleToLongBits(b) == negativeZeroDoubleBits)) {
            return b;
        }
        return (a <= b) ? a : b;
    }

}