optimize IGM for speed

pcigale/sed_modules/redshifting.py

@@ -125,8 +125,9 @@ def igm_transmission(wavelength, redshift):
     tau_norm_l_igm = np.interp(0, z_l, tau_l_igm)
     tau_norm_l_lls = np.interp(0, z_l, tau_l_lls)
     # Calculate tau_l_igm & tau_l_lls, assuming cross section ~ lambda^2.75 (O'Meara et al. 2013)
-    tau_l_igm[w] = tau_norm_l_igm * (z_l[w]+1)**2.75
-    tau_l_lls[w] = tau_norm_l_lls * (z_l[w]+1)**2.75
+    damp_factor = (z_l[w]+1)**2.75
+    tau_l_igm[w] = tau_norm_l_igm * damp_factor
+    tau_l_lls[w] = tau_norm_l_lls * damp_factor
 
     tau_taun = np.sum(tau_n[2:n_transitions_max, :], axis=0)