added to the startup file.

.travis.yml

@@ -5,6 +5,7 @@ virtualenv:
   system_site_packages: true
 before_install:
   - sudo apt-get install -qq python-numpy python-scipy python-matplotlib
+  - python simpeg/SimPEG/setup.py
 # command to install dependencies
 install: "pip install -r requirements.txt --use-mirrors"
 # command to run tests

SimPEG/forward/Problem.py

@@ -224,7 +224,7 @@ class Problem(object):
             The modelTransform changes the model into the physical property.
             The modelTransformDeriv provides the derivative of the modelTransform.
         """
-        return sp.eye(m.size)
+        return sp.identity(m.size)
 
     def createSyntheticData(self, m, std=0.05, u=None):
         """