From 324045f396d591be0d6d14657874278064299e62 Mon Sep 17 00:00:00 2001
From: Andreas Suter <andreas.suter@psi.ch>
Date: Thu, 2 Nov 2017 21:17:49 +0100
Subject: [PATCH] make sure that a valid covariance matrix is available after
 Hesse.

---
 src/classes/PFitter.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/classes/PFitter.cpp b/src/classes/PFitter.cpp
index 381693cf..82ea8971 100644
--- a/src/classes/PFitter.cpp
+++ b/src/classes/PFitter.cpp
@@ -1210,9 +1210,14 @@ Bool_t PFitter::ExecuteHesse()
   TString str = TString::Format("Hesse:    %.3f sec", (end-start)/1.0e3);
   fElapsedTime.push_back(str);
   if (!mnState.IsValid()) {
-    cerr << endl << ">> PFitter::ExecuteHesse(): **WARNING** Hesse encountered some problems!";
+    cerr << endl << ">> PFitter::ExecuteHesse(): **WARNING** Hesse encountered a problem! The state found is invalid.";
     cerr << endl;
     return false;
+  }
+  if (!mnState.HasCovariance()) {
+    cerr << endl << ">> PFitter::ExecuteHesse(): **WARNING** Hesse encountered a problem! No covariance matrix available.";
+    cerr << endl;
+    return false;
   }
 
   // fill parabolic errors