bug in the beam formula identified

AnaFringes/fringeV6.cc

@@ -395,12 +395,13 @@ r_8 Beam::Value(r_8 const xp[], r_8 const* Par) {
   } else {
 
 #if TYPE_BEAM == 1
-    lob = exp(-0.220544*x*x); //gaussian equivalent of J1 formula normalise a 1
+    //BUG JEC 20/9/19  the magic coeff was determined on spherical_bessel fonction and not the Bessel function  lob = exp(-0.220544*x*x); //gaussian equivalent of J1 formula normalise a 1
+    lob = exp(-0.280092*x*x); //gaussian equivalent of J1 formula normalise a 1
 #else
     if(x==0.) {
       lob = 1.;
     } else {
-      lob = 3. * boost::math::cyl_bessel_j(1, x)/x;
+      lob = 2. * boost::math::bessel_j(1, x)/x;
       lob *= lob; 
     }
 #endif