Removes possible division by zero from hypot

else/canny_impl.h

@@ -2,10 +2,10 @@
 
 
 /*
-  Version 1.0, 08.06.2015, Copyright University of Tbingen.
+  Version 1.0, 08.06.2015, Copyright University of Tübingen.
 
   The Code is created based on the method from the paper:
-  "ExCuSe: Robust Pupil Detection in Real-World Scenarios", W. Fuhl, T. C. Kbler, K. Sippel, W. Rosenstiel, E. Kasneci
+  "ExCuSe: Robust Pupil Detection in Real-World Scenarios", W. Fuhl, T. C. Kübler, K. Sippel, W. Rosenstiel, E. Kasneci
   CAIP 2015 : Computer Analysis of Images and Patterns
  
   The code and the algorithm are for non-comercial use only.
@@ -29,6 +29,9 @@ static float hypot(float a,float b)
     float t=a<b?a:b;
 	float x=a>b?a:b;
 
+    if (x==0)
+        return 0;
+
     t = t/x;
     return x*sqrt(1+(t*t));
 }
@@ -346,4 +349,4 @@ static cv::Mat canny_impl(cv::Mat *pic, cv::Mat *magni){
 
 
 
-}
\ No newline at end of file
+}