Converting TEvtGen to native cmake

[u/mrichter/AliRoot.git] / TEvtGen / EvtGen / EvtGenModels / EvtItgSimpsonIntegrator.cpp

diff --git a/TEvtGen/EvtGen/EvtGenModels/EvtItgSimpsonIntegrator.cpp b/TEvtGen/EvtGen/EvtGenModels/EvtItgSimpsonIntegrator.cpp
new file mode 100644 (file)
index 0000000..a39159d
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+++ b/TEvtGen/EvtGen/EvtGenModels/EvtItgSimpsonIntegrator.cpp
@@ -0,0 +1,99 @@
+//--------------------------------------------------------------------------
+//
+//
+// Copyright Information: See EvtGen/COPYRIGHT
+//
+// Environment:
+//      This software is part of the EvtGen package developed jointly
+//      for the BaBar and CLEO collaborations.  If you use all or part
+//      of it, please give an appropriate acknowledgement.
+//
+// Module: EvtItgSimpsonIntegrator.hh
+//
+// Description:
+//      Abstraction of a generic function for use in integration methods elsewhere
+//      in this package. (Stolen and modified from 
+//      the BaBar IntegrationUtils package - author: Phil Strother).
+//
+// Modification history:
+//
+//    Jane Tinslay                March 21, 2001       Module adapted for use in 
+//                                                     EvtGen
+//
+//------------------------------------------------------------------------
+#include "EvtGenBase/EvtPatches.hh"
+
+#include "EvtGenModels/EvtItgSimpsonIntegrator.hh"
+
+//-------------
+// C Headers --
+//-------------
+extern "C" {
+}
+
+//---------------
+// C++ Headers --
+//---------------
+
+#include <math.h>
+
+//-------------------------------
+// Collaborating Class Headers --
+//-------------------------------
+
+#include "EvtGenModels/EvtItgAbsFunction.hh"
+#include "EvtGenBase/EvtReport.hh"
+using std::endl;
+
+
+EvtItgSimpsonIntegrator::EvtItgSimpsonIntegrator(const EvtItgAbsFunction &theFunction, double precision, int maxLoop):
+  EvtItgAbsIntegrator(theFunction),
+  _precision(precision),
+  _maxLoop(maxLoop)
+{}
+
+
+//--------------
+// Destructor --
+//--------------
+
+EvtItgSimpsonIntegrator::~EvtItgSimpsonIntegrator()
+{}
+
+double
+EvtItgSimpsonIntegrator::evaluateIt(double lower, double higher) const{
+  
+  // report(INFO,"EvtGen")<<"in evaluate"<<endl;
+  int j;
+  double result(0.0);
+  double s, st, ost(0.0);
+  for (j=1;j<4;j++) {
+    st = trapezoid(lower, higher, j, result);
+    s = (4.0 * st - ost)/3.0;
+    ost=st;
+  }
+
+  double olds(s);
+  st = trapezoid(lower, higher, j, result);
+  s = (4.0 * st - ost)/3.0;
+
+  if (fabs(s - olds) < _precision*fabs(olds) || (s==0.0 && olds==0.0))     return s;
+  
+  ost=st;
+
+  for (j=5;j<_maxLoop;j++){
+
+    st = trapezoid(lower, higher, j, result);
+    s = (4.0 * st - ost)/3.0;
+    
+    if (fabs(s - olds) < _precision*fabs(olds) || (s==0.0 && olds==0.0))    return s;
+    olds=s;
+    ost=st;
+  }
+  
+  report(ERROR,"EvtGen") << "Severe error in EvtItgSimpsonIntegrator.  Failed to converge after loop with 2**"
+                << _maxLoop << " calls to the integrand in." << endl;
+  
+  return 0.0;
+    
+}