code: def circ(dec, dip, alpha):
      
      rad = old_div(np.pi, 180.)
      D_out, I_out = [], []
      dec, dip, alpha = dec * rad, dip * rad, alpha * rad
      dec1 = dec + old_div(np.pi, 2.)
      isign = 1
      if dip != 0:
          isign = (old_div(abs(dip), dip))
      dip1 = (dip - isign * (old_div(np.pi, 2.)))
      t = [[0, 0, 0], [0, 0, 0], [0, 0, 0]]
      v = [0, 0, 0]
      t[0][2] = np.cos(dec) * np.cos(dip)
      t[1][2] = np.sin(dec) * np.cos(dip)
      t[2][2] = np.sin(dip)
      t[0][1] = np.cos(dec) * np.cos(dip1)
      t[1][1] = np.sin(dec) * np.cos(dip1)
      t[2][1] = np.sin(dip1)
      t[0][0] = np.cos(dec1)
      t[1][0] = np.sin(dec1)
      t[2][0] = 0
      for i in range(101):
          psi = float(i) * np.pi / 50.
          v[0] = np.sin(alpha) * np.cos(psi)
          v[1] = np.sin(alpha) * np.sin(psi)
          v[2] = np.sqrt(abs(1. - v[0]**2 - v[1]**2))
          elli = [0, 0, 0]
          for j in range(3):
              for k in range(3):
                  elli[j] = elli[j] + t[j][k] * v[k]
          Dir = cart2dir(elli)
          D_out.append(Dir[0])
          I_out.append(Dir[1])
      return D_out, I_out
docs: function to calculate points on an circle about dec,dip with angle alpha