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From pste...@apache.org
Subject cvs commit: jakarta-commons/math/src/java/org/apache/commons/math/stat StatUtils.java
Date Wed, 01 Sep 2004 15:51:40 GMT
psteitz     2004/09/01 08:51:40

  Modified:    math/src/java/org/apache/commons/math/stat StatUtils.java
  Log:
  Javadoc. Made assumption about precomputed mean in variance computations explicit.
  
  Revision  Changes    Path
  1.32      +13 -3     jakarta-commons/math/src/java/org/apache/commons/math/stat/StatUtils.java
  
  Index: StatUtils.java
  ===================================================================
  RCS file: /home/cvs/jakarta-commons/math/src/java/org/apache/commons/math/stat/StatUtils.java,v
  retrieving revision 1.31
  retrieving revision 1.32
  diff -u -r1.31 -r1.32
  --- StatUtils.java	17 Jul 2004 22:01:39 -0000	1.31
  +++ StatUtils.java	1 Sep 2004 15:51:39 -0000	1.32
  @@ -343,6 +343,11 @@
        * See {@link org.apache.commons.math.stat.univariate.moment.Variance} for
        * details on the computing algorithm.
        * <p>
  +     * The formula used assumes that the supplied mean value is the arithmetic
  +     * mean of the sample data, not a known population parameter.  This method
  +     * is supplied only to save computation when the mean has already been
  +     * computed.
  +     * <p>
        * Returns 0 for a single-value (i.e. length = 1) sample.
        * <p>
        * Throws <code>IllegalArgumentException</code> if the array is null or
the
  @@ -364,10 +369,15 @@
       /**
        * Returns the variance of the entries in the input array, using the
        * precomputed mean value.  Returns <code>Double.NaN</code> if the array
  -     * is empty.
  +     * is empty.  
        * <p>
        * See {@link org.apache.commons.math.stat.univariate.moment.Variance} for
  -     * details on the computing algorithm.
  +     * details on the computing algorithm.   
  +     * <p>
  +     * The formula used assumes that the supplied mean value is the arithmetic
  +     * mean of the sample data, not a known population parameter.  This method
  +     * is supplied only to save computation when the mean has already been
  +     * computed.
        * <p>
        * Returns 0 for a single-value (i.e. length = 1) sample.
        * <p>
  
  
  

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