From d95c1714a939174693bd8da9199277241e61192a Mon Sep 17 00:00:00 2001
From: lmauviard <lucien@mauviard.fr>
Date: Fri, 6 Dec 2024 15:38:09 +0100
Subject: [PATCH] Moved the chi2 calculation to Signal.py

---
 xpsi/PostProcessing/_residual.py |  2 +-
 xpsi/Signal.py                   | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/xpsi/PostProcessing/_residual.py b/xpsi/PostProcessing/_residual.py
index a34037d4..7f60c5ac 100644
--- a/xpsi/PostProcessing/_residual.py
+++ b/xpsi/PostProcessing/_residual.py
@@ -337,7 +337,7 @@ def add_pulses( self ):
         double_pulse_model = _np.concatenate( (pulse_model , pulse_model) )
 
         # Compute the chi squared
-        chi2 = _np.sum( (pulse_data - pulse_model)**2 / pulse_model )
+        chi2 = self._signal.chi2
 
         # Plot pulse
         self._ax_pulse.errorbar(x=doubles_phases,
diff --git a/xpsi/Signal.py b/xpsi/Signal.py
index c2d579c5..bea5a442 100644
--- a/xpsi/Signal.py
+++ b/xpsi/Signal.py
@@ -733,6 +733,25 @@ def synthesise(self, phase_shifts, directory, **kwargs):
 
         """
         raise NotImplementedError('Cannot synthesise data.')
+    
+    @property
+    def chi2( self ):
+        """ Return the chi2 value for the current likelihood value or a given parameter vector if required.
+
+        :param list p:
+            Parameter vector, optional.
+
+        """
+
+        # Get the pulse of data and model
+        pulse_data = self.data.counts.sum( axis = 0 )
+        pulse_model = self.expected_counts.sum( axis = 0 )
+
+        # Compute the chi squared
+        chi2 = _np.sum( (pulse_data - pulse_model)**2 / pulse_model )
+
+        return chi2
+            
 
 
 def construct_energy_array(num_energies, signals, max_energy=None):