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changeset 879:43cd1c5e0955 stable

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bwdist: fix endless loop in bwdist with quasi-euclidean method in x86 systems. * bwdist.cc: in a 32-bit machine, use of float instead of double was somehow causing an endless loop (this may be treating the symptoms instead of the real cause) in specific matrices. Added a test that duplicated this bug. This was a regression caused by cset 27d87f06dd99 when changing the output class from double to single for Matlab compatibility.
author Carnë Draug <carandraug@octave.org>
date Sun, 09 Mar 2014 20:41:08 +0000
parents 72930d024906
children 4a96ec52e023
files src/bwdist.cc
diffstat 1 files changed, 25 insertions(+), 1 deletions(-) [+]
line wrap: on
line diff
--- a/src/bwdist.cc
+++ b/src/bwdist.cc
@@ -65,7 +65,7 @@
         }
     }
 
-  float olddist2, newdist2, newdistx, newdisty;
+  double olddist2, newdist2, newdistx, newdisty;
   bool changed;
 
   // Initialize index offsets for the current image width
@@ -641,5 +641,29 @@
 %! assert (dout, dist)
 %! assert (cout, c)
 
+## The quasi-euclidean method is apparently sensitive to a machine precision
+## error that happens in x86 systems only. This test will cause an endless
+## loop in case of a regression.
+%!test
+%! bw = [  0   1   1   0   0   0   1   0
+%!         0   0   0   0   0   0   0   0
+%!         1   1   0   0   0   0   0   0
+%!         0   0   0   0   0   0   1   0
+%!         0   0   0   0   1   0   0   1
+%!         0   0   0   0   0   0   0   0
+%!         1   0   0   0   0   0   0   0
+%!         0   0   1   0   0   1   1   0];
+%! out = single ([
+%! 1.00000   0.00000   0.00000   1.00000   2.00000   1.00000   0.00000   1.00000
+%! 1.00000   1.00000   1.00000   sqrt(2)   sqrt(2)+1 sqrt(2)   1.00000   sqrt(2)
+%! 0.00000   0.00000   1.00000   2.00000   2.00000   sqrt(2)   1.00000   sqrt(2)
+%! 1.00000   1.00000   sqrt(2)   sqrt(2)   1.00000   1.00000   0.00000   1.00000
+%! 2.00000   2.00000   2.00000   1.00000   0.00000   1.00000   1.00000   0.00000
+%! 1.00000   sqrt(2)   2.00000   sqrt(2)   1.00000   sqrt(2)   sqrt(2)   1.00000
+%! 0.00000   1.00000   1.00000   sqrt(2)   sqrt(2)   1.00000   1.00000   sqrt(2)
+%! 1.00000   1.00000   0.00000   1.00000   1.00000   0.00000   0.00000   1.00000
+%! ]);
+%! assert (bwdist (bw, "quasi-euclidean"), out);
+
 %!error <unknown METHOD> bwdist (bw, "not a valid method");
 */