Fixed division-by-zero issue in pow() which caused problems for GLC+ with sparse...

diff --git a/ChangeLog b/ChangeLog
index 748649a..10f6e80 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,6 @@
 git HEAD
 --------
+* Fixed division-by-zero issue in pow() which caused problems for GLC+ with sparse factors
 * Fixed bugs in unit test prob_test.cpp: replaced all occurences of
   BOOST_CHECK_CLOSE(...,(Real)0.0,tol) with BOOST_CHECK_SMALL(...,tol)
 * Merged Generalized Loop Correction code kindly provided by Siamak Ravanbakhsh

diff --git a/include/dai/util.h b/include/dai/util.h
index 3565ca0..dba4002 100644 (file)
--- a/include/dai/util.h
+++ b/include/dai/util.h
@@ -124,9 +124,15 @@ inline Real exp( Real x ) {
     return std::exp(x);
 }
 
-/// Returns \a to the power \a y
+/// Returns \a x to the power \a y
+/** We use the convention that division by zero yields zero;
+ *  for powers, this means that if \a x == 0.0 and \a y < 0.0, we 
+ *  return 0.0 instead of generating an error.
+ */
 inline Real pow( Real x, Real y ) {
     errno = 0;
+    if( x == 0.0 && y < 0.0 )
+        return 0.0;
     Real result = std::pow(x, y);
     DAI_DEBASSERT( errno == 0 );
     return result;