Fix bug: division by zero for N=1 (line|log)_scan

include/tksvm/phase_space/sweep/line_scan.hpp

@@ -66,7 +66,7 @@ namespace sweep {
         bool yield (point_type & point) {
             auto it_a = a.begin();
             auto it_b = b.begin();
-            double x = 1. * n / (N - 1);
+            double x = (N == 1) ? 0. : 1. * n / (N - 1);
             for (auto & c : point) {
                 c = *it_b * x + *it_a * (1. - x);
                 ++it_a, ++it_b;

include/tksvm/phase_space/sweep/log_scan.hpp

@@ -78,10 +78,11 @@ namespace sweep {
             for (size_t i = 0; i < point_type::label_dim;
                  ++i, ++it_a, ++it_b, ++it)
             {
+                double x = (N == 1) ? 0 : 1. * n / (N - 1);
                 if (is_log[i])
-                    *it = *it_a * pow(*it_b / *it_a, 1. * n / (N - 1));
+                    *it = *it_a * pow(*it_b / *it_a, x);
                 else
-                    *it = *it_a + (*it_b - *it_a) * n / (N - 1);
+                    *it = *it_a + (*it_b - *it_a) * x;
             }
             n = (n + 1) % size();
             return true;