Added an assert to check the lengthscale vector is half the size of the input

GPy/kern/src/multidimensional_integral_limits.py

@@ -23,6 +23,8 @@ class Multidimensional_Integral_Limits(Kern): #todo do I need to inherit from St
             lengthscale = np.ones(1)
         else:
             lengthscale = np.asarray(lengthscale)
+            
+        assert len(lengthscale)==input_dim/2
 
         self.lengthscale = Param('lengthscale', lengthscale, Logexp()) #Logexp - transforms to allow positive only values...
         self.variances = Param('variances', variances, Logexp()) #and here.