diff --git a/test/demo.py b/test/demo.py
index b47a07a..d0d6791 100644
--- a/test/demo.py
+++ b/test/demo.py
@@ -15,8 +15,9 @@ nm = np.matrix([x__,y__])
 cx = np.cov(nm)
 print cx.shape
 x = np.array([1.9,3])
-
-a = 1/ np.sqrt(2*np.pi)
+n = 2
+a = 1/ np.sqrt((2*np.pi**k)*np.det(cx))
+b = np.exp(() )
 #from scipy.stats import multivariate_normal
 #print multivariate_normal.pdf(x,u,cx)