code: def mni2tal(xin):
      
      if (not isinstance(xin, (tuple,list))) or (len(xin) != 3):
          raise ValueError('xin must be tuple/list with 3 coordinates')
  
      x = list(xin)
      # The input image is in RAS coordinates but we use ITK which returns LPS
      # coordinates.  So we need to flip the coordinates such that L => R and P => A to
      # get RAS (MNI) coordinates
      x[0] = x[0] * (-1)  # flip X
      x[1] = x[1] * (-1)  # flip Y
      
      xout = x
      
      if (x[2] >= 0):
          xout[0] = x[0] * 0.99
          xout[1] = x[1] * 0.9688 + 0.046 * x[2]
          xout[2] = x[1] * (-0.0485) + 0.9189 * x[2]
      
      if (x[2] < 0):
          xout[0] = x[0] * 0.99
          xout[1] = x[1] * 0.9688 + 0.042 * x[2]
          xout[2] = x[1] * (-0.0485) + 0.839 * x[2]
      
      return(xout)
docs: mni2tal for converting from ch2/mni space to tal - very approximate.
  
      This is a standard approach but it's not very accurate.
  
      ANTsR function: `mni2tal`
  
      Arguments
      ---------
      xin : tuple
          point in mni152 space.
  
      Returns
      -------
      tuple
  
      Example
      -------
      >>> import ants
      >>> ants.mni2tal( (10,12,14) )
  
      References
      ----------
      http://bioimagesuite.yale.edu/mni2tal/501_95733_More\%20Accurate\%20Talairach\%20Coordinates\%20SLIDES.pdf
      http://imaging.mrc-cbu.cam.ac.uk/imaging/MniTalairach