title: tensor flow giving nan loss when running with convolutional network
body: <p>I was trying to create a convolutional NN for house numbers images in tensorflow
  <a href="http://ufldl.stanford.edu/housenumbers/" rel="nofollow">http://ufldl.stanford.edu/housenumbers/</a></p>
  
  <p>I am getting cost as nan right in the first step when I am running my code.
  Here is the link to the github where I have put in my code
  <a href="https://github.com/ibnipun10/TensorFlow/blob/master/convhouseNumbers.ipynb" rel="nofollow">https://github.com/ibnipun10/TensorFlow/blob/master/convhouseNumbers.ipynb</a></p>
  
  <p>Please let me know where I am making mistake</p>