Fix cast exception when specifying ransac parameters

hgcalc.py

@@ -447,14 +447,14 @@ def main():
     z = 0.99  # total probability of success after all iterations
 
     if len(sys.argv) == 3:
-        threshold = sys.argv[2]
+        threshold = float(sys.argv[2])
     elif len(sys.argv) == 4:
-        threshold = sys.argv[2]
-        p = sys.argv[3]
+        threshold = float(sys.argv[2])
+        p = float(sys.argv[3])
     elif len(sys.argv) == 5:
-        threshold = sys.argv[2]
-        p = sys.argv[3]
-        z = sys.argv[4]
+        threshold = float(sys.argv[2])
+        p = float(sys.argv[3])
+        z = float(sys.argv[4])
     elif len(sys.argv) != 2:
         print('Usage: hgcalc <pairs_file_path> [threshold [valid_correspondence_probability [total_probability]]]')
         return