fix input models in brainpy.dyn (#172)

fix input models in brainpy.dyn

brainpy/dyn/neurons/input_models.py

@@ -64,10 +64,10 @@ def __init__(
     self.num_times = len(times)
 
     # data about times and indices
-    self.i = bm.Variable(jnp.zeros(1, dtype=bm.int_))
-    self.times = bm.Variable(jnp.asarray(times, dtype=bm.float_))
-    self.indices = bm.Variable(jnp.asarray(indices, dtype=bm.int_))
-    self.spike = bm.Variable(jnp.zeros(self.num, dtype=bool))
+    self.i = bm.Variable(bm.zeros(1, dtype=bm.int_))
+    self.times = bm.Variable(bm.asarray(times, dtype=bm.float_))
+    self.indices = bm.Variable(bm.asarray(indices, dtype=bm.int_))
+    self.spike = bm.Variable(bm.zeros(self.num, dtype=bool))
     if need_sort:
       sort_idx = bm.argsort(self.times)
       self.indices.value = self.indices[sort_idx]
@@ -121,8 +121,8 @@ def __init__(
     self.freqs = init_param(freqs, self.num, allow_none=False)
     self.dt = bm.get_dt() / 1000.
     self.size = (size,) if isinstance(size, int) else tuple(size)
-    self.spike = bm.Variable(jnp.zeros(self.num, dtype=bool))
-    self.t_last_spike = bm.Variable(jnp.ones(self.num) * -1e7)
+    self.spike = bm.Variable(bm.zeros(self.num, dtype=bool))
+    self.t_last_spike = bm.Variable(bm.ones(self.num) * -1e7)
     self.rng = bm.random.RandomState(seed=seed)
 
   def update(self, _t, _i):