Fix energy_bias_resolution_from_energy_dispersion

This function still assumed the wrong normalization of
the energy dispersion fixed in pyirf 0.10.

docs/changes/268.bugfix.rst

@@ -0,0 +1,4 @@
+Fix ``pyirf.benchmarks.energy_bias_resolution_from_energy_dispersion``.
+This function was not adapted to the now correct normalization of the
+energy dispersion matrix, resulting in wrong results on the now correct
+matrices.

pyirf/benchmarks/energy_bias_resolution.py

@@ -131,7 +131,8 @@ def energy_bias_resolution_from_energy_dispersion(
         Bin edges for the relative energy migration (``reco_energy / true_energy``)
     """
 
-    cdf = np.cumsum(energy_dispersion, axis=1)
+    bin_width = np.diff(migration_bins)
+    cdf = np.cumsum(energy_dispersion * bin_width[np.newaxis, :, np.newaxis], axis=1)
 
     n_energy_bins, _, n_fov_bins = energy_dispersion.shape
 

pyirf/benchmarks/tests/test_bias_resolution.py

@@ -105,6 +105,8 @@ def test_energy_bias_resolution():
         cdf[energy_bin, :, fov_bin] = norm.cdf(reco_energy, mu, sigma)
 
     edisp = cdf[:, 1:, :] - cdf[:, :-1, :]
+    bin_width = np.diff(migra_bins)
+    edisp /= bin_width[np.newaxis, :, np.newaxis]
 
     bias, resolution = energy_bias_resolution_from_energy_dispersion(
         edisp,