Put a simpler example, that doesn't crash...

tutorial/t7.geo

@@ -30,18 +30,20 @@ Line Loop(5) = {1,2,3,4};
 Plane Surface(6) = {5};
 
 Point(5) = {0.1,0.2,0,lc};
-Point(11) = {0.5,0.5,-1,lc};
+Point(11) = {0.4,0.7,-1,lc};
 Point(12) = {0.5,0.5,0,lc};
-Point(22) = {0.6,0.6,1,lc};
+Point(22) = {0.9,0.9,1,lc};
 
 Line(5) = {11,22};
 
 Spline(7) = {4,5,12,2};
 
-// Anisotropic attractors can be defined on points and lines:
+// Isotropic and anisotropic attractors can be defined on points and
+// lines:
 
-Attractor Line{5} = {.1, 0.01, 17};
+Attractor Point{1} = {0.01, 0.01, 2};
 
-Attractor Line{1,2} = {0.1, 0.005, 3};
-Attractor Line{7} = {0.1, 0.05, 3};
+Attractor Line{5} = {0.3, 0.01, 2};
+
+Attractor Line{7} = {0.1, 0.02, 8};