Merge pull request DGtal-team#1180 from isivigno/issue1099

check and correct implicit rounding issue 1099 + modify example file

Author: dcoeurjo

ChangeLog.md

@@ -84,6 +84,8 @@
    when displaying a small segment. Fix a non initialized attribute with
    some improvements on bounding box computation with orientation check.
    (B. Kerautret, [#1123](https://github.com/DGtal-team/DGtal/pull/1123))
+ - Frechet Shortcut: fix implicit rounding.
+   (I. Sivignon, [#1180](https://github.com/DGtal-team/DGtal/pull/1180))
 
 - *Image Package*
  - Fixing issue [#779](https://github.com/DGtal-team/DGtal/issues/779) by

examples/geometry/curves/exampleFrechetShortcut.cpp

@@ -55,19 +55,30 @@ int main( int argc, char** argv )
     trace.info() << " " << argv[ i ];
   trace.info() << endl;
 
-  std::string filename = examplesPath + "samples/plant-frechet.dat";
-  ifstream instream; // input stream
-  instream.open (filename.c_str(), ifstream::in);
-
+  std::string filename;
   double error;
-  if(argc < 3)
+  
+  if(argc == 1)
     {
-      trace.info() << "Maximum error not specified. Use default value (3).\n";
+      trace.info() << "Use default file and error value\n";
+      filename = examplesPath + "samples/plant-frechet.dat";
       error = 3;
     }
   else
-    error = atof(argv[1]);
-  trace.info() << error << endl;
+    if(argc != 3)
+      {
+	trace.info() << "Please enter a filename and error value.\n";
+	return 0;
+      }
+    else
+      {
+	filename = argv[1];
+	error = atof(argv[2]);
+      }
+  ifstream instream; // input stream
+  instream.open (filename.c_str(), ifstream::in);
+  
+
 
   Curve c; //grid curve
   c.initFromVectorStream(instream);

src/DGtal/geometry/curves/FrechetShortcut.h

@@ -356,20 +356,18 @@ namespace DGtal
       */
       static  bool isBetween(double i, double a, double b, double n)
       {
-	// if a<=b, a simple comparison enables to conclude
 	if(a<=b)
 	  if(i>=a && i<=b)
 	    return true;
 	  else
 	    return false;
 	else
 	  {
-	    //otherwise, translate the points such that a->0
-	    int tmp = a;
-	    a = fmod(a+n-tmp,n);
-	    b = fmod(b+n-tmp,n);
-	    i = fmod(i+n-tmp,n);
-	    return isBetween(i,a,b,n); 
+	    if((i>=a && i<=n) || (i>=0 && i<=b))
+	      return true;
+	    else
+	      return false;
+	    
 	  }
       }