Alignment: small variable name refactoring

Signed-off-by: Nicola VIGANÒ <nicola.vigano@esrf.fr>

nabu/preproc/alignment.py

@@ -35,11 +35,11 @@ def _get_lowpass_filter(img_shape, cutoff_pix, cutoff_trans_pix):
     k_cut_width = 0.5 / cutoff_trans_pix
 
     r = np.sqrt(np.sum(np.array(coords) ** 2, axis=0))
-    myargs = (r - k_cut) / k_cut_width
+    k_pos_rescaled = (r - k_cut) / k_cut_width
     if __have_scipy__:
-        res = spspe.erfc(myargs) / 2
+        res = spspe.erfc(k_pos_rescaled) / 2
     else:
-        res = np.array(list(map(math.erfc, myargs))) / 2
+        res = np.array(list(map(math.erfc, k_pos_rescaled))) / 2
 
     return res