STY: fix black issues

refellips/dataSE.py

@@ -4,6 +4,7 @@
 A basic representation of a 1D dataset
 """
 
+import copy
 import numpy as np
 import pandas as pd
 from refnx._lib import possibly_open_file

refellips/dispersion.py

@@ -562,9 +562,7 @@ def epsilon(self, energy):
             + Eg**2 * C**2
             - Ei**2 * (Ei**2 + 3 * Eg**2)
         )
-        a_atan = (energies**2 - Ei**2) * (
-            Ei**2 + Eg**2
-        ) + Eg**2 * C**2
+        a_atan = (energies**2 - Ei**2) * (Ei**2 + Eg**2) + Eg**2 * C**2
         alpha = np.sqrt(4 * Ei**2 - C**2)
         gamma = np.sqrt(Ei**2 - C**2 / 2)
         zeta4 = (energies**2 - gamma**2) ** 2 + 0.25 * alpha**2 * C**2
@@ -579,8 +577,7 @@ def epsilon(self, energy):
             / alpha
             / Ei
             * np.log(
-                (Ei**2 + Eg**2 + alpha * Eg)
-                / (Ei**2 + Eg**2 - alpha * Eg)
+                (Ei**2 + Eg**2 + alpha * Eg) / (Ei**2 + Eg**2 - alpha * Eg)
             )
         )
         e1 -= (

refellips/objectiveSE.py

@@ -379,8 +379,9 @@ def logl(self, pvals=None):
         # here just set it to unity
         y_err = 1
         if self.lnsigma is not None:
+            _model = np.r_[psi, delta]
             var_y = (
-                y_err * y_err + np.exp(2 * float(self.lnsigma)) * model * model
+                y_err * y_err + np.exp(2 * float(self.lnsigma)) * _model * _model
             )
         else:
             var_y = y_err**2