docs: def ZernikeSequence(x,y,maxRadial=5,epsilon=1e-10):
      """
      Return Zernike values at a given set of x,y coords up to some maximum 
      radial order
      """
      if maxRadial>5:
          raise ValueError('Code for higher radial orders not implemented')
      # Derive radius and exp(i*theta) 
      temp = x + 1j*y
      r1 = np.abs(temp)
      e1 = temp/(r1+epsilon)
       # Generate powers of r recursively
      r2 = r1*r1
      r3 = r2*r1
      r4 = r3*r1
      r5 = r4*r1
      # Generate cos and sin terms recursively from exp(i*theta)
      e2 = e1*e1
      e3 = e2*e1
      e4 = e3*e1
      e5 = e4*e1
      ctheta = e1.real
      stheta = e1.imag
      c2theta = e2.real
      s2theta = e2.imag
      c3theta = e3.real
      s3theta = e3.imag
      c4theta = e4.real
      s4theta = e4.imag
      c5theta = e5.real
      s5theta = e5.imag
      # Generate all the zernikes
      zernike = np.zeros((21,)+x.shape )
      zernike[0] =  1.0
      zernike[1] =  2.0*r1*ctheta
      zernike[2] =  2.0*r1*stheta
      zernike[3] =  sqrt(3.0)*(2.0*r2 - 1.0)
      zernike[4] =  sqrt(6.0)*r2*s2theta
      zernike[5] =  sqrt(6.0)*r2*c2theta
      zernike[6] =  sqrt(8.0)*(3.0*r3 - 2.0*r1)*stheta
      zernike[7] =  sqrt(8.0)*(3.0*r3 - 2.0*r1)*ctheta
      zernike[8] =  sqrt(8.0)*r3*s3theta
      zernike[9] = sqrt(8.0)*r3*c3theta
      zernike[10] = sqrt(5.0)*(6.*r4 - 6.*r2 + 1.)
      zernike[11] = sqrt(10.)*(4.*r4 - 3.*r2)*c2theta
      zernike[12] = sqrt(10.)*(4.*r4 - 3.*r2)*s2theta
      zernike[13] = sqrt(10.)*r4*c4theta
      zernike[14] = sqrt(10.)*r4*s4theta
      zernike[15] = sqrt(12.)*(10*r5-12*r3+3*r1)*ctheta
      zernike[16] = sqrt(12.)*(10*r5-12*r3+3*r1)*stheta
      zernike[17] = sqrt(12.)*(5*r5-4*r3)*c3theta
      zernike[18] = sqrt(12.)*(5*r5-4*r3)*s3theta
      zernike[19] = sqrt(12.)*r5*c5theta
      zernike[20] = sqrt(12.)*r5*s5theta
      # Make zernike zero outside unit circle (useful for dot product)
      zernike = zernike*np.less_equal(r1, 1.0)
      return(zernike[:NumZernike(maxRadial)])