[RF] Improve RooVoigtian documentation

roofit/roofit/inc/RooVoigtian.h

@@ -16,27 +16,25 @@
 #ifndef ROO_VOIGTIAN
 #define ROO_VOIGTIAN
 
-#include "RooAbsPdf.h"
-#include "RooRealProxy.h"
-
-class RooRealVar;
+#include <RooAbsPdf.h>
+#include <RooRealProxy.h>
 
 class RooVoigtian : public RooAbsPdf {
 public:
-  RooVoigtian() {} ;
+  RooVoigtian() {}
   RooVoigtian(const char *name, const char *title,
          RooAbsReal& _x, RooAbsReal& _mean,
               RooAbsReal& _width, RooAbsReal& _sigma,
               bool doFast = false);
   RooVoigtian(const RooVoigtian& other, const char* name=nullptr) ;
   TObject* clone(const char* newname) const override { return new RooVoigtian(*this,newname); }
-  inline ~RooVoigtian() override { }
-
-// These methods allow the user to select the fast evaluation
-// of the complex error function using look-up tables
-// (default is the "slow" CERNlib algorithm)
 
+  /// Enable the fast evaluation of the complex error function using look-up
+  /// tables (default is the "slow" CERNlib algorithm).
   inline void selectFastAlgorithm()    { _doFast = true;  }
+
+  /// Disable the fast evaluation of the complex error function using look-up
+  /// tables (default is the "slow" CERNlib algorithm).
   inline void selectDefaultAlgorithm() { _doFast = false; }
 
 protected:
@@ -52,7 +50,7 @@ class RooVoigtian : public RooAbsPdf {
 
 private:
 
-  bool _doFast;
+  bool _doFast = false;
   ClassDefOverride(RooVoigtian,2) // Voigtian PDF (Gauss (x) BreitWigner)
 };
 

roofit/roofit/src/RooVoigtian.cxx

@@ -23,20 +23,34 @@ function (the default CERNlib C335 algorithm, and a faster, look-up-table
 based method). By default, RooVoigtian employs the default (CERNlib)
 algorithm. Select the faster algorithm either in the constructor, or with
 the selectFastAlgorithm() method.
+
+\Note The "width" parameter that determines the Breit-Wigner shape
+      represents the **full width at half maximum (FWHM)** of the
+      Breit-Wigner (often referred to as \f$\Gamma\f$ or \f$2\gamma\f$).
 **/
 
-#include "RooVoigtian.h"
-#include "RooRealVar.h"
-#include "RooMath.h"
-#include "RooBatchCompute.h"
+#include <RooVoigtian.h>
+
+#include <RooMath.h>
+#include <RooBatchCompute.h>
 
 #include <cmath>
 #include <complex>
-using namespace std;
 
 ClassImp(RooVoigtian);
 
 ////////////////////////////////////////////////////////////////////////////////
+/// Construct a RooVoigtian PDF, which represents the convolution of a
+/// Breit-Wigner with a Gaussian.
+/// \param name Name that identifies the PDF in computations.
+/// \param title Title for plotting.
+/// \param _x The observable for the PDF.
+/// \param _mean The mean of the distribution.
+/// \param _width The **full width at half maximum (FWHM)** of the Breit-Wigner
+///               (often referred to as \f$\Gamma\f$ or \f$2\gamma\f$).
+/// \param _sigma The width of the Gaussian distribution.
+/// \param doFast Use the faster look-up-table-based method for the evaluation
+///               of the complex error function.
 
 RooVoigtian::RooVoigtian(const char *name, const char *title,
           RooAbsReal& _x, RooAbsReal& _mean,
@@ -79,7 +93,7 @@ double RooVoigtian::evaluate() const
   if (s==0.) return (1./(arg*arg+0.25*w*w));
 
   // Gauss for zero width
-  if (w==0.) return exp(coef*arg*arg);
+  if (w==0.) return std::exp(coef*arg*arg);
 
   // actual Voigtian for non-trivial width and sigma
   double c = 1./(sqrt(2.)*s);