Now we generate the true plummer distribution.

Doc/noDist/Notes/distribution.tex

@@ -107,9 +107,9 @@ If you consider the
 \subsection{Plummer Model}
 This is a hard test case in astrophysics problem, and it models a globular cluster of stars, which is highly non uniform.  It is called   the plummer distribution. To construct such distribution, first we construct a uniform points distribution on the unit sphere. Second, the radius is chosen according to the plummer distribution (double power law in astrophysics). We consider $u$ a random number between 0 and 1, then the associated radius is given by
 \begin{equation*}
-r = \sqrt{\frac{u^{2/3}}{u^{2/3}-1}}
+r = 1.0/\sqrt{u^{-2/3}-1},
 \end{equation*}
-
+and the total mass is one. Then, $m_i = \frac{1}{Npt}$.
 \begin{figure}[h]
   \centering
   \begin{minipage}{0.45\textwidth}%
@@ -140,6 +140,8 @@ The corresponding potential is
 \begin{equation}
 \Phi_P(r) = - \frac{G M}{\sqrt{r^2+a^2}}
 \end{equation}
+
+In N-body units, $G = M = 1$ and $a = 3\pi/16 \sim 0.589$
 \subsection{Diagonal Model}
 
 %, shape end size=.5cm},decoration={shape start size=.5cm, shape end size=.125cm

Examples/generateDistributions.cpp

@@ -97,7 +97,7 @@ namespace Param {
     const FParameterNames Size
     = {{"-size"}, "Size of the geometry a:b:c - default values are 1.0:1.0:2.0"};
     const FParameterNames Radius
-    = {{"-radius"}, "used to specified the radius of the sphere an dthe plummer distribution or R - default value for R is 2.0"};
+    = {{"-radius"}, "used to specified the radius of the sphere and the plummer distribution or R - default value for R is 2.0"};
     const FParameterNames Charge
     = {{"-charge"}, "generate physical values between -1 and 1 otherwise generate between 0 and 1"};
     const FParameterNames ZM
@@ -250,6 +250,10 @@ int main(int argc, char ** argv){
     std::cout << "End of writing" <<std::endl;
 
     //  Generate  file for visualization
+//    if(FParameters::existParameter(argc, argv, FParameterDefinitions::OutputVisuFile.options)){
+//        std::string outfilename(FParameters::getStr(argc,argv,FParameterDefinitions::OutputFile.options,   "output.vtp"));
+//        driverExportData(outfilename, particles , NbPoints,loader.getNbRecordPerline() );
+//    }
     if(FParameters::existParameter(argc, argv, FParameterDefinitions::OutputVisuFile.options)) {
         std::string visufile(FParameters::getStr(argc, argv, FParameterDefinitions::OutputVisuFile.options, "output.vtp"));
         driverExportData(visufile, particles , NbPoints);

Src/Files/FGenerateDistribution.hpp

@@ -243,12 +243,12 @@ FReal plummerDist(FSize& cpt, const FReal &R) {
     }
 }
 
-
 /**
  * \brief Build N points following the Plummer distribution
  *
  * First we construct N points uniformly distributed on the unit sphere. Then
- * the radius in construct according to the Plummr distribution.
+ * the radius in construct according to the Plummer distribution for
+ * a  constant mass of 1/N
  *
  * \tparam FReal Floating point type
  *
@@ -259,6 +259,32 @@ FReal plummerDist(FSize& cpt, const FReal &R) {
 template <class FReal>
 void unifRandomPlummer(const FSize N, const FReal R, FReal * points) {
     unifRandomPointsOnSphere<FReal>(N, 1, points);
+    FReal mc = 1.0/static_cast<FReal>(N);
+    for (FSize i = 0, j = 0 ; i< N ; ++i, j+=4)  {
+    	FReal m = getRandom<FReal>();
+    	FReal r = FMath::Sqrt( 1.0/(FMath::pow(m, -2.0/3.0) - 1.0)) ;
+        points[j]    *= r;
+        points[j+1]  *= r;
+        points[j+2]  *= r;
+        points[j+3]   = mc;  // the mass
+    }
+}
+/**
+ * \brief Build N points following the Plummer like distribution
+ *
+ * First we construct N points uniformly distributed on the unit sphere. Then
+ * the radius in construct according to the Plummer like distribution.
+ *
+ * \tparam FReal Floating point type
+ *
+ * \param N the number of points following the Plummer distribution
+ * \param R the radius of the sphere that contains all the points
+ * \param points array of size 4*N and stores data as follow x,y,z,0,x,y,z,0....
+ */
+template <class FReal>
+void unifRandomPlummerLike(const FSize N, const FReal R, FReal * points) {
+	FReal a = 1.0 ;
+    unifRandomPointsOnSphere<FReal>(N, 1, points);
     FReal r, rm = 0.0;
     FSize cpt = 0;
     for (FSize i = 0, j = 0 ; i< N ; ++i, j+=4)  {