Access to AliRoot magnetic field map.

diff --git a/TFluka/magfld.cxx b/TFluka/magfld.cxx
new file mode 100644 (file)
index 0000000..2161e43
--- /dev/null
+++ b/TFluka/magfld.cxx
@@ -0,0 +1,74 @@
+#include "AliRun.h"
+#include "AliMagF.h"
+#include "Fdblprc.h"  //(DBLPRC) fluka common
+//
+// #include "TCallf77.h"
+
+#ifndef WIN32
+#define magfld magfld_
+#define type_of_call
+#else
+#define magfld MAGFLD
+#define type_of_call  _stdcall
+#endif
+
+extern "C" void type_of_call magfld(double& x,   double& y,   double& z, 
+                                   double& btx, double& bty, double& btz, double& b, 
+                                   int&    nreg,int& idisc)
+{
+
+/*
+*----------------------------------------------------------------------*
+*                                                                      *
+*                                                                      *
+*     Input variables:                                                 *
+*            x,y,z = current position                                  *
+*            nreg  = current region                                    *
+*     Output variables:                                                *
+*            btx,bty,btz = cosines of the magn. field vector           *
+*            B = magnetic field intensity (Tesla)                      *
+*            idisc = set to 1 if the particle has to be discarded      *
+*                                                                      *
+*----------------------------------------------------------------------*
+*/
+
+    printf("\n ========> magfld\n");
+    
+    
+    idisc = 0;
+    
+    Float_t bc[3];
+    Float_t xc[3];
+    
+    xc[1] = x;
+    xc[0] = y;
+    xc[2] = z;
+    
+    
+       
+    gAlice->Field()->Field(xc, bc);
+    
+    b = sqrt(bc[0] * bc[0] + bc[1] * bc[1] + bc[2] * bc[2]);
+    if (b) {
+       btx = bc[1]/b;
+       bty = bc[0]/b;
+       Double_t btt = btx * btx + bty * bty;
+       if (btt >= (Double_t) 1.) {
+           btx /= TMath::Sqrt(btt);
+           bty /= TMath::Sqrt(btt);
+           b   /= TMath::Sqrt(btt);
+           btz =  (Double_t) 0.;
+       } else {
+           btz = TMath::Sqrt((Double_t) 1. -  btt);
+       }
+    } else {
+       btx = 0.;
+       bty = 0.;
+       btz = 1.;
+    }
+    
+    // from kG to T
+    b /= (Double_t) 10.;
+    printf("\n #magfld: x, y, z, btx, bty, btz, b %f %f %f %f %f %f %f \n", 
+          x, y, z, btx, bty, btz, b);
+}