title: How to calculate a Normal Distribution percent point function in python
body: <p>How do I do the equivalent of <code>scipy.stats.norm.ppf</code> without using Scipy. I have python's Math module has <code>erf</code> built in but I cannot seem to recreate the function.</p>
  
  <p>PS: I cannot just use scipy because Heroku does not allow you to install it and using alternate buildpacks breaches the 300Mb maximum slug size limit.</p>