title: Creating several grids at a time
body: <p>I have a matrix that contains start and end points, and want to create grids in-between these. For now this is linear, but I would like to be able to also use this for nonlinear grids (of my own).</p>
  
  <pre><code>test = np.array([[0.1, 0.5], [0.0001, 0.9]]) #start points in row 0, end points in row 1
  nL = 10 # number of grid points
  np.hstack((np.linspace(0.1, 0.0001, nL).reshape((-1,1)), np.linspace(0.5, 0.9, nL).reshape((-1,1)))) 
  # expected output. 
  array([[ 0.1  ,  0.5  ],
         [ 0.089,  0.544],
         [ 0.078,  0.589],
         [ 0.067,  0.633],
         [ 0.056,  0.678],
         [ 0.045,  0.722],
         [ 0.033,  0.767],
         [ 0.022,  0.811],
         [ 0.011,  0.856],
         [ 0.   ,  0.9  ]])
  </code></pre>
  
  <p>For now, this relies on stacking <code>linspace</code> which is not really nice and readable. What's a more clean way to achieve this?</p>