Fix failing tests

Author: lucianopaz

pymc3/distributions/multivariate.py

@@ -598,7 +598,7 @@ def __init__(self, n, p, *args, **kwargs):
 
         p = p / tt.sum(p, axis=-1, keepdims=True)
 
-        if len(self.shape) >= 1:
+        if len(self.shape) > 1:
             self.n = tt.shape_padright(n)
             self.p = p if p.ndim > 1 else tt.shape_padleft(p)
         else:
@@ -607,9 +607,10 @@ def __init__(self, n, p, *args, **kwargs):
             self.p = tt.as_tensor_variable(p)
 
         self.mean = self.n * self.p
-        mode_ind = tt.argmax(self.p, axis=-1, keepdims=True)
-        mode = tt.zeros_like(self.mean, dtype=self.dtype)
-        mode = tt.inc_subtensor(mode[..., mode_ind], 1)
+        mode = tt.cast(tt.round(self.mean), "int32")
+        diff = self.n - tt.sum(mode, axis=-1, keepdims=True)
+        inc_bool_arr = tt.abs_(diff) > 0
+        mode = tt.inc_subtensor(mode[inc_bool_arr.nonzero()], diff[inc_bool_arr.nonzero()])
         self.mode = mode
 
     def _random(self, n, p, size=None, raw_size=None):