fix bug in name

pyatsoleiloutils/readmatfile.py

@@ -33,7 +33,7 @@ def readmomapmat(
     momap_pn = numpy.copy(momap_pn.T)
     s_indexes=f['momap']['s_indexes'][:]
     s_array=f['momap']['s_array'][:]
-    first_element_index = f['momap']['first_element_index'][:]
+    index_first_element = f['momap']['index_first_element'][:]
     f.close()
 
     return momap_pn, s_indexes, s_array, first_element_index