title: Is there a way of working in spherical coordinates in SymPy?
body: <p>I am working in a script to do analytical calculations in Python. For it I would need vector representation of my parameters and also some basic vector operations such as Gradient and Divergence, and for this reason I started working in SymPy. However, I noticed there is not a straightforward way of working in spherical coordinates.</p>
  
  <p>After reading the documentation I found out a Cartessian environment can be simply defined as</p>
  
  <pre><code>from sympy.vector import CoordSys3D
  
  N = CoordSys3D('N')
  </code></pre>
  
  <p>and directly start working with the unitary cartessian unitary vectors i, j, k</p>
  
  <pre><code>v = 2*N.i + 3*N.j - N.k
  </code></pre>
  
  <p>Is there any way of initializing such an environment for spherical coordinates where I have access to radial, theta and phi unitary vectors, and consequently the basic  vector operations are done accordingly?
  Thank you so much in advance!</p>