FIX: process trajectories only when x_dot is None

Author: yb6599

pysindy/pysindy.py

@@ -396,7 +396,8 @@ def fit(
             x, t, x_dot, u, self.feature_library
         )
 
-        x, x_dot = self._process_trajectories(x, t, x_dot)
+        if x_dot is None:
+            x, x_dot = self._process_trajectories(x, t, x_dot)
 
         if u is None:
             self.n_control_features_ = 0
@@ -500,7 +501,8 @@ def score(self, x, t, x_dot=None, u=None, metric=r2_score, **metric_kws):
 
         x_dot_predict = self.predict(x, u)
 
-        x, x_dot = self._process_trajectories(x, t, x_dot)
+        if x_dot is None:
+            x, x_dot = self._process_trajectories(x, t, x_dot)
 
         x_dot = concat_sample_axis(x_dot)
         x_dot_predict = concat_sample_axis(x_dot_predict)