Quick fix for infinite loop: drop extra precision in step computation.

I am not saying this is what the code should optimally look like...


git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/trunk@3590 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: 0253d73afb1b1b565b45d214ea2d948e00c7db25

1 files changed, 8 insertions, 0 deletions

diff --git a/src/Bottleneck_distance/include/gudhi/Bottleneck.h b/src/Bottleneck_distance/include/gudhi/Bottleneck.h
index 41f8b16a..b0fc3949 100644
--- a/src/Bottleneck_distance/include/gudhi/Bottleneck.h
+++ b/src/Bottleneck_distance/include/gudhi/Bottleneck.h
@@ -30,6 +30,7 @@
 #include <limits>  // for numeric_limits
 
 #include <cmath>
+#include <cfloat>  // FLT_EVAL_METHOD
 
 namespace Gudhi {
 
@@ -43,6 +44,13 @@ double bottleneck_distance_approx(Persistence_graph& g, double e) {
   Graph_matching biggest_unperfect(g);
   while (b_upper_bound - b_lower_bound > 2 * e) {
     double step = b_lower_bound + (b_upper_bound - b_lower_bound) / alpha;
+#if !defined FLT_EVAL_METHOD || FLT_EVAL_METHOD < 0 || FLT_EVAL_METHOD > 1
+    // On platforms where double computation is done with excess precision,
+    // we force it to its true precision so the following test is reliable.
+    volatile double drop_excess_precision = step;
+    step = drop_excess_precision;
+    // Alternative: step = CGAL::IA_force_to_double(step);
+#endif
     if (step <= b_lower_bound || step >= b_upper_bound)  // Avoid precision problem
       break;
     m.set_r(step);