[R-gregmisc-users] SF.net SVN: r-gregmisc:[2020] pkg/gtools/R/dirichlet.R

[<wa...@us...>]

Revision: 2020
          http://sourceforge.net/p/r-gregmisc/code/2020
Author:   warnes
Date:     2015-05-23 22:12:57 +0000 (Sat, 23 May 2015)
Log Message:
-----------
ddirichlet() was incorrectly returning NA when x[i]=0 and
alpha[i]=1.  In this case, the one calculation became (-Inf * 0),
which R evaluates to NaN.   The correction is to detect this case and
substitute -Inf instead of NaN.

Modified Paths:
--------------
    pkg/gtools/R/dirichlet.R

Modified: pkg/gtools/R/dirichlet.R
===================================================================
--- pkg/gtools/R/dirichlet.R	2015-05-08 22:49:28 UTC (rev 2019)
+++ pkg/gtools/R/dirichlet.R	2015-05-23 22:12:57 UTC (rev 2020)
@@ -29,9 +29,9 @@
   dirichlet1 <- function(x, alpha)
     {
       logD <- sum(lgamma(alpha)) - lgamma(sum(alpha))
-      s<-sum((alpha-1)*log(x))
+      s <-(alpha-1)*log(x)
+      s <- ifelse(alpha==1 & x==0, -Inf, s)
       exp(sum(s)-logD)
-
     }
 
   # make sure x is a matrix

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