diff --git a/GPy/inference/latent_function_inference/posterior.py b/GPy/inference/latent_function_inference/posterior.py
index 3e5022aa..b3a352e5 100644
--- a/GPy/inference/latent_function_inference/posterior.py
+++ b/GPy/inference/latent_function_inference/posterior.py
@@ -14,7 +14,7 @@ class Posterior(object):
     schemes and the model classes.
 
     """
-    def __init__(self, woodbury_chol=None, woodbury_vector=None, K=None, mean=None, cov=None, K_chol=None):
+    def __init__(self, woodbury_chol=None, woodbury_vector=None, K=None, mean=None, cov=None, K_chol=None, woodbury_inv=None):
         """
         woodbury_chol : a lower triangular matrix L that satisfies posterior_covariance = K - K L^{-T} L^{-1} K
         woodbury_vector : a matrix (or vector, as Nx1 matrix) M which satisfies posterior_mean = K M
@@ -45,7 +45,9 @@ class Posterior(object):
         #obligatory
         self._K = K
 
-        if ((woodbury_chol is not None) and (woodbury_vector is not None) and (K is not None)) or ((mean is not None) and (cov is not None) and (K is not None)):
+        if ((woodbury_chol is not None) and (woodbury_vector is not None))\
+                or ((woodbury_inv is not None) and (woodbury_vector is not None))\
+                or ((mean is not None) and (cov is not None)):
             pass # we have sufficient to compute the posterior
         else:
             raise ValueError, "insufficient information to compute the posterior"
@@ -56,13 +58,16 @@ class Posterior(object):
         self._woodbury_chol = woodbury_chol
         self._woodbury_vector = woodbury_vector
 
+        #option 2.
+        self._woodbury_inv = woodbury_inv
+        #and woodbury vector
+
         #option 2:
         self._mean = mean
         self._covariance = cov
 
         #compute this lazily
         self._precision = None
-        self._woodbury_inv = None
 
     @property
     def mean(self):
@@ -99,7 +104,6 @@ class Posterior(object):
             symmetrify(self._woodbury_inv)
         return self._woodbury_inv
 
-
     @property
     def woodbury_vector(self):
         if self._woodbury_vector is None:
diff --git a/GPy/inference/latent_function_inference/varDTC.py b/GPy/inference/latent_function_inference/varDTC.py
index b5ba4c2d..e6a96aa2 100644
--- a/GPy/inference/latent_function_inference/varDTC.py
+++ b/GPy/inference/latent_function_inference/varDTC.py
@@ -2,7 +2,7 @@
 # Licensed under the BSD 3-clause license (see LICENSE.txt)
 
 from posterior import Posterior
-from ...util.linalg import jitchol, backsub_both_sides, tdot, dtrtrs
+from ...util.linalg import jitchol, backsub_both_sides, tdot, dtrtrs, dpotri, symmetrify
 import numpy as np
 log_2_pi = np.log(2*np.pi)
 
@@ -163,7 +163,7 @@ class VarDTC(object):
         else:
             lik_1 = -0.5 * num_data * output_dim * (np.log(2.*np.pi) - np.log(beta)) - 0.5 * beta * trYYT
             lik_2 = -0.5 * output_dim * (np.sum(beta * psi0) - np.trace(A))
-        lik_3 = -output_dim * (np.sum(np.log(np.diag(LB)))) # + 0.5 * num_inducing * np.log(sf2))
+        lik_3 = -output_dim * (np.sum(np.log(np.diag(LB))))
         lik_4 = 0.5 * data_fit
         log_marginal = lik_1 + lik_2 + lik_3 + lik_4
 
@@ -178,6 +178,7 @@ class VarDTC(object):
             kern.update_gradients_sparse(X=X, Z=Z, **grad_dict)
 
         #get sufficient things for posterior prediction
+        #TODO: do we really want to do this in  the loop?
         if VVT_factor.shape[1] == Y.shape[1]:
             woodbury_vector = Cpsi1Vf # == Cpsi1V
         else:
@@ -185,11 +186,13 @@ class VarDTC(object):
             tmp, _ = dtrtrs(Lm, np.asfortranarray(psi1V), lower=1, trans=0)
             tmp, _ = dpotrs(LB, tmp, lower=1)
             woodbury_vector, _ = dtrtrs(Lm, tmp, lower=1, trans=1)
-        #TODO: totally wrong, fix.
-        woodbury_chol = np.eye(num_inducing)
+        Bi, _ = dpotri(LB, lower=0)
+        symmetrify(Bi)
+        woodbury_inv = backsub_both_sides(Lm, np.eye(num_inducing) - Bi)
+
 
         #construct a posterior object
-        post = Posterior(woodbury_chol=woodbury_chol, woodbury_vector=woodbury_vector, K=Kmm, mean=None, cov=None, K_chol=Lm)
+        post = Posterior(woodbury_inv=woodbury_inv, woodbury_vector=woodbury_vector, K=Kmm, mean=None, cov=None, K_chol=Lm)
 
         return post, log_marginal, grad_dict
 
diff --git a/GPy/plotting/matplot_dep/models_plots.py b/GPy/plotting/matplot_dep/models_plots.py
index a4e06441..b3178d0c 100644
--- a/GPy/plotting/matplot_dep/models_plots.py
+++ b/GPy/plotting/matplot_dep/models_plots.py
@@ -5,6 +5,7 @@ import pylab as pb
 import numpy as np
 import Tango
 from base_plots import gpplot, x_frame1D, x_frame2D
+from ...util.misc import param_to_array
 
 
 def plot_fit(model, plot_limits=None, which_data_rows='all',
@@ -95,8 +96,11 @@ def plot_fit(model, plot_limits=None, which_data_rows='all',
 
         #add inducing inputs (if a sparse model is used)
         if hasattr(model,"Z"):
-            Zu = model.Z[:,free_dims] * model._Xscale[:,free_dims] + model._Xoffset[:,free_dims]
-            ax.plot(Zu, np.zeros_like(Zu) + ax.get_ylim()[0], 'r|', mew=1.5, markersize=12)
+            #Zu = model.Z[:,free_dims] * model._Xscale[:,free_dims] + model._Xoffset[:,free_dims]
+            Zu = param_to_array(model.Z[:,free_dims])
+            z_height = ax.get_ylim()[0]
+            ax.plot(Zu, np.zeros_like(Zu) + z_height, 'r|', mew=1.5, markersize=12)
+
 
         #add error bars for uncertain (if input uncertainty is being modelled)
         if hasattr(model,"has_uncertain_inputs"):
@@ -144,7 +148,8 @@ def plot_fit(model, plot_limits=None, which_data_rows='all',
 
         #add inducing inputs (if a sparse model is used)
         if hasattr(model,"Z"):
-            Zu = model.Z[:,free_dims] * model._Xscale[:,free_dims] + model._Xoffset[:,free_dims]
+            #Zu = model.Z[:,free_dims] * model._Xscale[:,free_dims] + model._Xoffset[:,free_dims]
+            Zu = model.Z[:,free_dims]
             ax.plot(Zu[:,free_dims[0]], Zu[:,free_dims[1]], 'wo')
 
     else: