2011/12/5 Sébastien Brisard <sebastien.bris...@m4x.org>: > Hi Mikkel, >> It seems like only the test was changed in r1210359 (svn diff -r >> 1210359). This does _not_ correspond to the log (svn log -r 1210359). > > Here is an excerpt of the email sent automatically when I committed > revision 1210359 > > ==========BEGIN EXCERPT========== > Author: celestin > Date: Mon Dec 5 08:15:38 2011 > New Revision: 1210359 > > URL: http://svn.apache.org/viewvc?rev=1210359&view=rev > Log: > - Corrected expressions for mean and variance in > distribution.PascalDistribution (MATH-715). > - Made javadoc more explicit > - Restored SVN properties to various files in package distribution. > > .................... > > Modified: > commons/proper/math/trunk/src/main/java/org/apache/commons/math/distribution/PascalDistribution.java > URL: > http://svn.apache.org/viewvc/commons/proper/math/trunk/src/main/java/org/apache/commons/math/distribution/PascalDistribution.java?rev=1210359&r1=1210358&r2=1210359&view=diff > ============================================================================== > --- > commons/proper/math/trunk/src/main/java/org/apache/commons/math/distribution/PascalDistribution.java > (original) > +++ > commons/proper/math/trunk/src/main/java/org/apache/commons/math/distribution/PascalDistribution.java > Mon Dec 5 08:15:38 2011 > @@ -31,10 +31,25 @@ import org.apache.commons.math.util.Fast > * </p> > * <p> > * There are various ways to express the probability mass and distribution > - * functions for the Pascal distribution. The convention employed by the > - * library is to express these functions in terms of the number of failures > in > - * a Bernoulli experiment > - * (see <a > href="http://en.wikipedia.org/wiki/Negative_binomial_distribution#Waiting_time_in_a_Bernoulli_process";>Waiting > Time in a Bernoulli Process</a>). > + * functions for the Pascal distribution. The present implementation > represents > + * the distribution of the number of failures before {@code r} successes > occur. > + * This is the convention adopted in e.g. > + * <a > href="http://mathworld.wolfram.com/NegativeBinomialDistribution.html";>MathWorld</a>, > + * but <em>not</em> in > + * <a > href="http://en.wikipedia.org/wiki/Negative_binomial_distribution";>Wikipedia</a>. > + * </p> > + * <p> > + * For a random variable {@code X} whose values are distributed > according to this > + * distribution, the probability mass function is given by<br/> > + * {@code P(X = k) = C(k + r - 1, r - 1) * p^r * (1 - p)^k,}<br/> > + * where {@code r} is the number of successes, {@code p} is the probability > of > + * success, and {@code X} is the total number of failures. {@code C(n, k)} is > + * the binomial coefficient ({@code n} choose {@code k}). The mean and > variance > + * of {@code X} are<br/> > + * {@code E(X) = (1 - p) * r / p, var(X) = (1 - p) * r / p^2.}<br/> > + * Finally, the cumulative distribution function is given by<br/> > + * {@code P(X <= k) = I(p, r, k + 1)}, > + * where I is the regularized incomplete Beta function. > * </p> > * > * @see <a href="http://en.wikipedia.org/wiki/Negative_binomial_distribution";> > @@ -159,25 +174,24 @@ public class PascalDistribution extends > * {@inheritDoc} > * > * For number of successes {@code r} and probability of success {@code p}, > - * the mean is {@code (r * p) / (1 - p)}. > + * the mean is {@code r * (1 - p) / p}. > */ > public double getNumericalMean() { > final double p = getProbabilityOfSuccess(); > final double r = getNumberOfSuccesses(); > - return (r * p) / (1 - p); > + return (r * (1 - p)) / p; > } > > /** > * {@inheritDoc} > * > * For number of successes {@code r} and probability of success {@code p}, > - * the variance is {@code (r * p) / (1 - p)^2}. > + * the variance is {@code r * (1 - p) / p^2}. > */ > public double getNumericalVariance() { > final double p = getProbabilityOfSuccess(); > final double r = getNumberOfSuccesses(); > - final double pInv = 1 - p; > - return (r * p) / (pInv * pInv); > + return r * (1 - p) / (p * p); > } > > ==========END EXCERPT========== > > It seems to me that everything (?) is OK? > >> >> It seems like the changes was done in r1210358. Is that true? >> > I don't think so (see extract below). > > ==========BEGIN EXCERPT========== > > Author: sgoeschl > Date: Mon Dec 5 08:02:46 2011 > New Revision: 1210358 > > URL: http://svn.apache.org/viewvc?rev=1210358&view=rev > Log: > [maven-release-plugin] prepare for next development iteration > > Modified: > commons/proper/email/trunk/pom.xml > > ==========END EXCERPT========== > > I don't really understand what is happening. I hope I didn't mess up > anything this morning. Please keep me posted. > Sébastien > Hi,
Now I looked it through and it looks good to me - and also the SVN behaves fine again (it could also be mine that acted weird). Thanks again for fixing this. Cheers, Mikkel. --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org For additional commands, e-mail: dev-h...@commons.apache.org
