diff --git a/src/libraries/AMPTOOLS_AMPS/BreitWigner.cc b/src/libraries/AMPTOOLS_AMPS/BreitWigner.cc
index 3dfc84ef1..c501eae43 100644
--- a/src/libraries/AMPTOOLS_AMPS/BreitWigner.cc
+++ b/src/libraries/AMPTOOLS_AMPS/BreitWigner.cc
@@ -61,7 +61,13 @@ BreitWigner::calcAmplitude( GDouble** pKin ) const
   GDouble mass  = Ptot.M();
   GDouble mass1 = P1.M();
   GDouble mass2 = P2.M();
-  
+
+  return calcAmplitudeFromMasses( mass, mass1, mass2 );
+}
+
+complex< GDouble >
+BreitWigner::calcAmplitudeFromMasses( GDouble mass, GDouble mass1, GDouble mass2 ) const
+{
   // assert positive breakup momenta     
   GDouble q0 = fabs( breakupMomentum(m_mass0, mass1, mass2) );
   GDouble q  = fabs( breakupMomentum(mass,    mass1, mass2) );
diff --git a/src/libraries/AMPTOOLS_AMPS/BreitWigner.h b/src/libraries/AMPTOOLS_AMPS/BreitWigner.h
index 9312ac434..fca51597c 100644
--- a/src/libraries/AMPTOOLS_AMPS/BreitWigner.h
+++ b/src/libraries/AMPTOOLS_AMPS/BreitWigner.h
@@ -36,6 +36,7 @@ class BreitWigner : public UserAmplitude< BreitWigner >
 	string name() const { return "BreitWigner"; }
   
   complex< GDouble > calcAmplitude( GDouble** pKin ) const;
+  complex< GDouble > calcAmplitudeFromMasses( GDouble mass, GDouble mass1, GDouble mass2 ) const;
 	  
   void updatePar( const AmpParameter& par );
     
diff --git a/src/libraries/AMPTOOLS_AMPS/BreitWigner3body.cc b/src/libraries/AMPTOOLS_AMPS/BreitWigner3body.cc
index e2c7cb072..0898ce1ba 100644
--- a/src/libraries/AMPTOOLS_AMPS/BreitWigner3body.cc
+++ b/src/libraries/AMPTOOLS_AMPS/BreitWigner3body.cc
@@ -46,9 +46,14 @@ BreitWigner3body::calcAmplitude( GDouble** pKin ) const
   
   GDouble mass  = Ptot.M();
   
+  return calcAmplitudeFromMasses( mass );
+}
+
+complex< GDouble >
+BreitWigner3body::calcAmplitudeFromMasses( GDouble mass ) const
+{
   GDouble width = m_width0;
-  //GDouble width = m_width0;
-  
+
   // this first factor just gets normalization right for BW's that have
   // no additional s-dependence from orbital L
   complex<GDouble> bwtop( sqrt( m_mass0 * m_width0 / 3.1416 ), 0.0 );
diff --git a/src/libraries/AMPTOOLS_AMPS/BreitWigner3body.h b/src/libraries/AMPTOOLS_AMPS/BreitWigner3body.h
index 235f7cac6..eb0116905 100644
--- a/src/libraries/AMPTOOLS_AMPS/BreitWigner3body.h
+++ b/src/libraries/AMPTOOLS_AMPS/BreitWigner3body.h
@@ -36,6 +36,7 @@ class BreitWigner3body : public UserAmplitude< BreitWigner3body >
 	string name() const { return "BreitWigner3body"; }
   
   complex< GDouble > calcAmplitude( GDouble** pKin ) const;
+  complex< GDouble > calcAmplitudeFromMasses( GDouble mass ) const;
 	  
   void updatePar( const AmpParameter& par );