Add TMath.BreitWigner function

Author: linev

scripts/JSRootCore.js

@@ -1857,6 +1857,7 @@
                  this._math = JSROOT.Math;
                  _func = _func.replace(/TMath::Prob\(/g, 'this._math.Prob(')
                               .replace(/TMath::Gaus\(/g, 'this._math.Gaus(')
+                              .replace(/TMath::BreitWigner\(/g, 'this._math.BreitWigner(')
                               .replace(/xygaus\(/g, 'this._math.gausxy(this, x, y, ')
                               .replace(/gaus\(/g, 'this._math.gaus(this, x, ')
                               .replace(/gausn\(/g, 'this._math.gausn(this, x, ')

scripts/JSRootMath.js

@@ -637,6 +637,11 @@
       return Math.exp(-0.5 * Math.pow((x-mean) / sigma, 2));
    };
 
+   /** @memberOf JSROOT.Math */
+   JSROOT.Math.BreitWigner = function(x, mean, gamma) {
+      return gamma/((x-mean)*(x-mean) + gamma*gamma/4) / 2 / Math.PI;
+   }
+
    /** @memberOf JSROOT.Math */
    JSROOT.Math.gaus = function(f, x, i) {
       // function used when gaus(0) used in the TFormula