ensure dlsim output length

bnavigator · bnavigator · commit d3658639466e · 2021-03-26T14:08:54.000+01:00
diff --git a/control/timeresp.py b/control/timeresp.py
@@ -355,12 +355,13 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False,
                              'Parameter ``T``: ', squeeze=True,
                              transpose=transpose)
 
-    # equally spaced also implies strictly monotonic increase
-    dt = T[1] - T[0]
+    n_steps = T.shape[0]            # number of simulation steps
+
+    # equally spaced also implies strictly monotonic increase,
+    dt = (T[-1] - T[0]) / (n_steps - 1)
     if not np.allclose(np.diff(T), dt):
         raise ValueError("Parameter ``T``: time values must be "
                          "equally spaced.")
-    n_steps = T.shape[0]            # number of simulation steps
 
     # create X0 if not given, test if X0 has correct shape
     X0 = _check_convert_array(X0, [(n_states,), (n_states, 1)],
@@ -432,12 +433,24 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False,
 
             # Now check to make sure it is a multiple (with check against
             # sys.dt because floating point mod can have small errors
-            elif not (np.isclose(dt % sys.dt, 0) or
-                      np.isclose(dt % sys.dt, sys.dt)):
+            if not (np.isclose(dt % sys.dt, 0) or
+                    np.isclose(dt % sys.dt, sys.dt)):
                 raise ValueError("Time steps ``T`` must be multiples of "
                                  "sampling time")
             sys_dt = sys.dt
 
+            # sp.signal.dlsim returns not enough samples if
+            # T[-1] - T[0] < sys_dt * decimation * (n_steps - 1)
+            # due to rounding errors. Give it an additional time step
+            # to discard
+            decimation_dt = (T[-1] - T[0]) / (n_steps - 1)
+            if (decimation_dt / sys_dt) % 1. > 0.5:
+                T = np.append(T, T[-1] + decimation_dt)
+                if U.ndim == 1:
+                    U = np.append(U, U[-1])
+                else:
+                    U = np.append(U, U[:, -1], 1)
+
         else:
             sys_dt = dt         # For unspecified sampling time, use time incr
 
