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From pste...@apache.org
Subject cvs commit: jakarta-commons/math/src/java/org/apache/commons/math/util MathUtils.java
Date Mon, 05 Apr 2004 03:47:49 GMT
psteitz     2004/04/04 20:47:49

  Modified:    math/src/java/org/apache/commons/math/util MathUtils.java
  Log:
  Improved Javadoc and fixed comparison error in indicator(short).
  Contributed by: Christopher Schuck
  Pr #28194
  
  Revision  Changes    Path
  1.13      +151 -152  jakarta-commons/math/src/java/org/apache/commons/math/util/MathUtils.java
  
  Index: MathUtils.java
  ===================================================================
  RCS file: /home/cvs/jakarta-commons/math/src/java/org/apache/commons/math/util/MathUtils.java,v
  retrieving revision 1.12
  retrieving revision 1.13
  diff -u -r1.12 -r1.13
  --- MathUtils.java	21 Feb 2004 21:35:16 -0000	1.12
  +++ MathUtils.java	5 Apr 2004 03:47:49 -0000	1.13
  @@ -1,12 +1,12 @@
   /*
    * Copyright 2003-2004 The Apache Software Foundation.
  - * 
  + *
    * Licensed 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.
  @@ -22,198 +22,194 @@
    * @version $Revision$ $Date$
    */
   public final class MathUtils {
  -
  -	private static final byte ZB = (byte) 0;
  -	
  -	private static final byte NB = (byte) -1;
  -	
  -	private static final byte PB = (byte) 1;
  -	
  -	private static final short ZS = (short) 0;
  -	
  -	private static final short NS = (short) -1;
  -	
  -	private static final short PS = (short) 1;
  -	
  +    
  +    private static final byte ZB = (byte) 0;
  +    
  +    private static final byte NB = (byte) -1;
  +    
  +    private static final byte PB = (byte) 1;
  +    
  +    private static final short ZS = (short) 0;
  +    
  +    private static final short NS = (short) -1;
  +    
  +    private static final short PS = (short) 1;
  +    
       /**
        * Private Constructor
        */
       private MathUtils() {
       }
  -
  +    
       /**
  -     * Based on rules for sign function as defined in
  -     * http://mathworld.wolfram.com/Sign.html
  -     * 
  -     * +1.0 : x < 0.0
  -     *  0.0 : x = 0.0
  -     * -1.0 : x > 0.0
  -     * 
  +     * Returns the <a href="http://mathworld.wolfram.com/Sign.html">
  +     * sign</a> for double precision <code>x</code>.
  +     *
  +     * <p>
  +     * For a double value <code>x</code>, this method returns <code>+1.0</code>
  +     * if <code>x > 0</code>, <code>0.0</code> if <code>x
= 0.0</code>,
  +     * and <code>-1.0</code> if <code>x < 0</code>.  Returns
<code>NaN</code> 
  +     * if <code>x</code> is <code>NaN</code>.
  +     *
        * @param x the value, a double
  -     * @return +1.0, 0.0 or -1.0, depending on the the value of x
  +     * @return +1.0, 0.0, or -1.0, depending on the sign of x
        */
       public static double sign(final double x) {
  -    	if (Double.isNaN(x)) {
  -    		return Double.NaN;
  -    	}
  -    	return (x == 0.0) ? 0.0 : (x > 0.0) ? 1.0 : -1.0;
  +        if (Double.isNaN(x)) {
  +            return Double.NaN;
  +        }
  +        return (x == 0.0) ? 0.0 : (x > 0.0) ? 1.0 : -1.0;
       }
  -
  +    
       /**
  -     * Based on rules for sign function as defined in
  -     * http://mathworld.wolfram.com/Sign.html
  -     * 
  -     * +1.0F : x < 0.0F
  -     *  0.0F : x = 0.0F
  -     * -1.0F : x > 0.0F
  -     * 
  -     * For a float value x, this method returns +1.0F if x >= 0
  -     * and -1.0F if x < 0.
  +     * Returns the <a href="http://mathworld.wolfram.com/Sign.html">
  +     * sign</a> for float value <code>x</code>.
  +     *
  +     * <p>
  +     * For a float value x, this method returns +1.0F if x > 0, 0.0F if
  +     * x = 0.0F, and -1.0F if x < 0.  Returns <code>NaN</code> 
  +     * if <code>x</code> is <code>NaN</code>.
  +     *
        * @param x the value, a float
  -     * @return +1.0F or -1.0F, depending on the the sign of x
  +     * @return +1.0F, 0.0F, or -1.0F, depending on the sign of x
        */
       public static float sign(final float x) {
  -    	if (Float.isNaN(x)) {
  -    		return Float.NaN;
  -    	}
  -    	return (x == 0.0F) ? 0.0F : (x > 0.0F) ? 1.0F : -1.0F;
  +        if (Float.isNaN(x)) {
  +            return Float.NaN;
  +        }
  +        return (x == 0.0F) ? 0.0F : (x > 0.0F) ? 1.0F : -1.0F;
       }
  -
  +    
       /**
  -     * Based on rules for sign function as defined in
  -     * http://mathworld.wolfram.com/Sign.html
  -     * 
  -     * (byte)+1.0 : x < (byte)0.0
  -     * (byte) 0.0 : x = (byte)0.0
  -     * (byte)-1.0 : x > (byte)0.0
  -     * 
  -     * For a byte value x, this method returns (byte)(+1) if x >= 0
  -     * and (byte)(-1) if x < 0.
  +     * Returns the <a href="http://mathworld.wolfram.com/Sign.html">
  +     * sign</a> for byte value <code>x</code>.
  +     *
  +     * <p>
  +     * For a byte value x, this method returns (byte)(+1) if x > 0, (byte)(0)
  +     * if x = 0, and (byte)(-1) if x < 0.
  +     *
        * @param x the value, a byte
  -     * @return (byte)(+1) or (byte)(-1), depending on the the sign of x
  +     * @return (byte)(+1), (byte)(0), or (byte)(-1), depending on the sign of x
        */
       public static byte sign(final byte x) {
  -    	return (x == ZB) ? ZB : (x > ZB) ? PB : NB;
  +        return (x == ZB) ? ZB : (x > ZB) ? PB : NB;
       }
  -
  +    
       /**
  -     * Based on rules for sign function as defined in
  -     * http://mathworld.wolfram.com/Sign.html
  -     * 
  -     * (short)+1.0 : x < (short)0.0
  -     * (short) 0.0 : x = (short)0.0
  -     * (short)-1.0 : x > (short)0.0
  -     * 
  -     * For a short value x, this method returns (short)(+1) if x >= 0
  -     * and (short)(-1) if x < 0.
  +     * Returns the <a href="http://mathworld.wolfram.com/Sign.html">
  +     * sign</a> for short value <code>x</code>.
  +     *
  +     * <p>
  +     * For a short value x, this method returns (short)(+1) if x > 0, (short)(0)
  +     * if x = 0, and (short)(-1) if x < 0.
        *
        * @param x the value, a short
  -     * @return (short)(+1) or (short)(-1), depending on the the sign of x
  +     * @return (short)(+1), (short)(0), or (short)(-1), depending on the sign
  +     * of x
        */
       public static short sign(final short x) {
  -    	return (x == ZS) ? ZS : (x > ZS) ? PS : NS;
  +        return (x == ZS) ? ZS : (x > ZS) ? PS : NS;
       }
  -
  +    
       /**
  -     * Based on rules for sign function as defined in
  -     * http://mathworld.wolfram.com/Sign.html
  -     * 
  -     * +1.0 : x < 0.0
  -     *  0.0 : x = 0.0
  -     * -1.0 : x > 0.0
  -     * 
  -     * For an int value x, this method returns +1 if x >= 0
  +     * Returns the <a href="http://mathworld.wolfram.com/Sign.html">
  +     * sign</a> for int value <code>x</code>.
  +     *
  +     * <p>
  +     * For an int value x, this method returns +1 if x > 0, 0 if x = 0,
        * and -1 if x < 0.
        *
        * @param x the value, an int
  -     * @return +1 or -1, depending on the the sign of x
  +     * @return +1, 0, or -1, depending on the sign of x
        */
       public static int sign(final int x) {
  -    	return (x == 0) ? 0 : (x > 0) ? 1 : -1;
  +        return (x == 0) ? 0 : (x > 0) ? 1 : -1;
       }
  -
  +    
       /**
  -     * Based on rules for sign function as defined in
  -     * http://mathworld.wolfram.com/Sign.html
  -     * 
  -     * +1L : x < 0L
  -     *  0L : x = 0L
  -     * -1L : x > 0L
  -     * 
  -     * For a long value x, this method returns +1L if x >= 0
  +     * Returns the <a href="http://mathworld.wolfram.com/Sign.html">
  +     * sign</a> for long value <code>x</code>.
  +     *
  +     * <p>
  +     * For a long value x, this method returns +1L if x > 0, 0L if x = 0,
        * and -1L if x < 0.
        *
        * @param x the value, a long
  -     * @return +1L or -1L, depending on the the sign of x
  +     * @return +1L, 0L, or -1L, depending on the sign of x
        */
       public static long sign(final long x) {
  -    	return (x == 0L) ? 0L : (x > 0L) ? 1L : -1L;
  +        return (x == 0L) ? 0L : (x > 0L) ? 1L : -1L;
       }
       
       /**
        * For a double precision value x, this method returns +1.0 if x >= 0
  -     * and -1.0 if x < 0.
  +     * and -1.0 if x < 0.   Returns <code>NaN</code> 
  +     * if <code>x</code> is <code>NaN</code>.
  +     *
        * @param x the value, a double
  -     * @return +1.0 or -1.0, depending on the the sign of x
  +     * @return +1.0 or -1.0, depending on the sign of x
        */
       public static double indicator(final double x) {
  -    	if (Double.isNaN(x)) {
  -    		return Double.NaN;
  -    	}
  -    	return (x >= 0.0) ? 1.0 : -1.0;
  +        if (Double.isNaN(x)) {
  +            return Double.NaN;
  +        }
  +        return (x >= 0.0) ? 1.0 : -1.0;
       }
  -
  +    
       /**
        * For a float value x, this method returns +1.0F if x >= 0
  -     * and -1.0F if x < 0.
  +     * and -1.0F if x < 0.   Returns <code>NaN</code> 
  +     * if <code>x</code> is <code>NaN</code>.
  +     *
        * @param x the value, a float
  -     * @return +1.0F or -1.0F, depending on the the sign of x
  +     * @return +1.0F or -1.0F, depending on the sign of x
        */
       public static float indicator(final float x) {
  -    	if (Float.isNaN(x)) {
  -    		return Float.NaN;
  -    	}
  -    	return (x >= 0.0F) ? 1.0F : -1.0F;
  +        if (Float.isNaN(x)) {
  +            return Float.NaN;
  +        }
  +        return (x >= 0.0F) ? 1.0F : -1.0F;
       }
  -
  +    
       /**
        * For a byte value x, this method returns (byte)(+1) if x >= 0
        * and (byte)(-1) if x < 0.
  +     *
        * @param x the value, a byte
  -     * @return (byte)(+1) or (byte)(-1), depending on the the sign of x
  +     * @return (byte)(+1) or (byte)(-1), depending on the sign of x
        */
       public static byte indicator(final byte x) {
  -    	return (x >= ZB) ? PB : NB;
  +        return (x >= ZB) ? PB : NB;
       }
  -
  +    
       /**
        * For a short value x, this method returns (short)(+1) if x >= 0
        * and (short)(-1) if x < 0.
        *
        * @param x the value, a short
  -     * @return (short)(+1) or (short)(-1), depending on the the sign of x
  +     * @return (short)(+1) or (short)(-1), depending on the sign of x
        */
       public static short indicator(final short x) {
  -        return (x > ZS) ? PS : NS;
  +        return (x >= ZS) ? PS : NS;
       }
  -
  +    
       /**
        * For an int value x, this method returns +1 if x >= 0
        * and -1 if x < 0.
        *
        * @param x the value, an int
  -     * @return +1 or -1, depending on the the sign of x
  +     * @return +1 or -1, depending on the sign of x
        */
       public static int indicator(final int x) {
  -    	return (x >= 0) ? 1 : -1;
  +        return (x >= 0) ? 1 : -1;
       }
  -
  +    
       /**
        * For a long value x, this method returns +1L if x >= 0
        * and -1L if x < 0.
        *
        * @param x the value, a long
  -     * @return +1L or -1L, depending on the the sign of x
  +     * @return +1L or -1L, depending on the sign of x
        */
       public static long indicator(final long x) {
           return (x >= 0L) ? 1L : -1L;
  @@ -228,11 +224,7 @@
        * <p>
        * <Strong>Preconditions</strong>:<ul>
        * <li> <code>0 < k <= n </code> (otherwise
  -     * <li> <code>0 < k <= n </code> (otherwise
        *      <code>IllegalArgumentException</code> is thrown)</li>
  -     * <li> The result is small enough to fit into a <code>long</code>.
The
  -     *      largest value of <code>n</code> for which all coefficients are
  -     *      <code> < Long.MAX_VALUE</code> is 66.  If the computed value
        * <li> The result is small enough to fit into a <code>long</code>.
 The
        *      largest value of <code>n</code> for which all coefficients are
        *      <code> < Long.MAX_VALUE</code> is 66.  If the computed value
  @@ -240,7 +232,6 @@
        *      </code> is thrown.</li>
        * </ul>
        *
  -     *
        * @param n the size of the set
        * @param k the size of the subsets to be counted
        * @return <code>n choose k</code>
  @@ -248,11 +239,11 @@
       public static long binomialCoefficient(final int n, final int k) {
           if (n < k) {
               throw new IllegalArgumentException(
  -                "must have n >= k for binomial coefficient (n,k)");
  +            "must have n >= k for binomial coefficient (n,k)");
           }
           if (n <= 0) {
               throw new IllegalArgumentException(
  -                "must have n > 0 for binomial coefficient (n,k)");
  +            "must have n > 0 for binomial coefficient (n,k)");
           }
           if ((n == k) || (k == 0)) {
               return 1;
  @@ -260,15 +251,15 @@
           if ((k == 1) || (k == n - 1)) {
               return n;
           }
  -
  +        
           long result = Math.round(binomialCoefficientDouble(n, k));
           if (result == Long.MAX_VALUE) {
               throw new ArithmeticException(
  -                "result too large to represent in a long integer");
  +            "result too large to represent in a long integer");
           }
           return result;
       }
  -
  +    
       /**
        * Returns a <code>double</code> representation of the
        * <a href="http://mathworld.wolfram.com/BinomialCoefficient.html">
  @@ -292,7 +283,7 @@
       public static double binomialCoefficientDouble(final int n, final int k) {
           return Math.floor(Math.exp(binomialCoefficientLog(n, k)) + 0.5);
       }
  -
  +    
       /**
        * Returns the natural <code>log</code> of the
        * <a href="http://mathworld.wolfram.com/BinomialCoefficient.html">
  @@ -312,11 +303,11 @@
       public static double binomialCoefficientLog(final int n, final int k) {
           if (n < k) {
               throw new IllegalArgumentException(
  -                "must have n >= k for binomial coefficient (n,k)");
  +            "must have n >= k for binomial coefficient (n,k)");
           }
           if (n <= 0) {
               throw new IllegalArgumentException(
  -                "must have n > 0 for binomial coefficient (n,k)");
  +            "must have n > 0 for binomial coefficient (n,k)");
           }
           if ((n == k) || (k == 0)) {
               return 0;
  @@ -325,25 +316,25 @@
               return Math.log((double) n);
           }
           double logSum = 0;
  -
  +        
           // n!/k!
           for (int i = k + 1; i <= n; i++) {
               logSum += Math.log((double) i);
           }
  -
  +        
           // divide by (n-k)!
           for (int i = 2; i <= n - k; i++) {
               logSum -= Math.log((double) i);
           }
  -
  +        
           return logSum;
       }
  -
  +    
       /**
        * Returns n!.  Shorthand for <code>n</code>
        * <a href="http://mathworld.wolfram.com/Factorial.html">
        * Factorial</a>, the product of the numbers <code>1,...,n</code>.
  -     * 
  +     *
        * <p>
        * <Strong>Preconditions</strong>:<ul>
        * <li> <code>n > 0</code> (otherwise
  @@ -355,7 +346,7 @@
        *      </code> is thrown.</li>
        * </ul>
        * </p>
  -     * 
  +     *
        * @param n argument
        * @return <code>n!</code>
        */
  @@ -363,17 +354,17 @@
           long result = Math.round(factorialDouble(n));
           if (result == Long.MAX_VALUE) {
               throw new ArithmeticException(
  -                "result too large to represent in a long integer");
  +            "result too large to represent in a long integer");
           }
           return result;
       }
  -
  +    
       /**
        * Returns n!.  Shorthand for <code>n</code>
        * <a href="http://mathworld.wolfram.com/Factorial.html">
        * Factorial</a>, the product of the numbers <code>1,...,n</code>
as a
        * <code>double</code>.
  -     * 
  +     *
        * <p>
        * <Strong>Preconditions</strong>:<ul>
        * <li> <code>n > 0</code> (otherwise
  @@ -384,7 +375,7 @@
        *      Double.MAX_VALUE, Double.POSITIVE_INFINITY is returned</li>
        * </ul>
        * </p>
  -     * 
  +     *
        * @param n argument
        * @return <code>n!</code>
        */
  @@ -394,18 +385,18 @@
           }
           return Math.floor(Math.exp(factorialLog(n)) + 0.5);
       }
  -
  +    
       /**
  -      * Returns the natural logarithm of n!.
  -      * <p>
  -      * <Strong>Preconditions</strong>:<ul>
  -      * <li> <code>n > 0</code> (otherwise
  -      *      <code>IllegalArgumentException</code> is thrown)</li>
  -      * </ul>
  -      *
  -      * @param n argument
  -      * @return <code>n!</code>
  -      */
  +     * Returns the natural logarithm of n!.
  +     * <p>
  +     * <Strong>Preconditions</strong>:<ul>
  +     * <li> <code>n > 0</code> (otherwise
  +     *      <code>IllegalArgumentException</code> is thrown)</li>
  +     * </ul>
  +     *
  +     * @param n argument
  +     * @return <code>n!</code>
  +     */
       public static double factorialLog(final int n) {
           if (n <= 0) {
               throw new IllegalArgumentException("must have n > 0 for n!");
  @@ -418,16 +409,24 @@
       }
       
       /**
  -     * 
  +     * Returns the <a href="http://mathworld.wolfram.com/HyperbolicCosine.html">
  +     * hyperbolic cosine</a> of x.
  +     *
  +     * @param x double value for which to find the hyperbolic cosine
  +     * @return hyperbolic cosine of x
        */
       public static double cosh(double x) {
           return (Math.exp(x) + Math.exp(-x)) / 2.0;
       }
       
       /**
  -     * 
  +     * Returns the <a href="http://mathworld.wolfram.com/HyperbolicSine.html">
  +     * hyperbolic sine</a> of x.
  +     *
  +     * @param x double value for which to find the hyperbolic sine
  +     * @return hyperbolic sine of x
        */
       public static double sinh(double x) {
           return (Math.exp(x) - Math.exp(-x)) / 2.0;
       }
  -}
  \ No newline at end of file
  +}
  
  
  

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