[RF] Allow scientific notation in JSONfactory formula

Fixes #14637

Author: ferdymercury

hist/hist/inc/TFormula.h

@@ -156,7 +156,6 @@ class TFormula : public TNamed
    static Bool_t IsOperator(const char c);
    static Bool_t IsBracket(const char c);
    static Bool_t IsFunctionNameChar(const char c);
-   static Bool_t IsScientificNotation(const TString & formula, int ipos);
    static Bool_t IsHexadecimal(const TString & formula, int ipos);
    static Bool_t IsAParameterName(const TString & formula, int ipos);
    void   ExtractFunctors(TString &formula);
@@ -238,6 +237,8 @@ class TFormula : public TNamed
       return fHessFuncPtr != nullptr;
    }
 
+   static Bool_t IsScientificNotation(const TString & formula, int ipos);
+
    // template <class T>
    // T Eval(T x, T y = 0, T z = 0, T t = 0) const;
    template <class T>

roofit/hs3/src/JSONFactories_RooFitCore.cxx

@@ -65,19 +65,24 @@ namespace {
  * arguments are returned as a vector of strings.
  *
  * @param expr A string representing a mathematical expression.
- * @return A vector of strings representing the extracted arguments.
+ * @return A set of unique strings representing the extracted arguments.
  */
-std::vector<std::string> extractArguments(std::string expr)
+std::set<std::string> extractArguments(std::string expr)
 {
    // Get rid of whitespaces
    expr.erase(std::remove_if(expr.begin(), expr.end(), [](unsigned char c) { return std::isspace(c); }), expr.end());
 
-   std::vector<std::string> arguments;
+   std::set<std::string> arguments;
    size_t startidx = expr.size();
    for (size_t i = 0; i < expr.size(); ++i) {
       if (startidx >= expr.size()) {
          if (isalpha(expr[i])) {
             startidx = i;
+            // check this character is not part of scientific notation, e.g. 2e-5
+            if (TFormula::IsScientificNotation(expr, i)) {
+               // if it is, we ignore this character
+               startidx = expr.size();
+            }
          }
       } else {
          if (!isdigit(expr[i]) && !isalpha(expr[i]) && expr[i] != '_') {
@@ -87,12 +92,12 @@ std::vector<std::string> extractArguments(std::string expr)
             }
             std::string arg(expr.substr(startidx, i - startidx));
             startidx = expr.size();
-            arguments.push_back(arg);
+            arguments.insert(arg);
          }
       }
    }
    if (startidx < expr.size()) {
-      arguments.push_back(expr.substr(startidx));
+      arguments.insert(expr.substr(startidx));
    }
    return arguments;
 }

roofit/hs3/test/testRooFitHS3.cxx

@@ -23,6 +23,7 @@
 #include <RooRealVar.h>
 #include <RooSimultaneous.h>
 #include <RooWorkspace.h>
+#include <RooFormulaVar.h>
 
 #include <TROOT.h>
 
@@ -404,3 +405,35 @@ TEST(RooFitHS3, SimultaneousGaussians)
    int status = validate(simPdf);
    EXPECT_EQ(status, 0);
 }
+
+// https://github.com/root-project/root/issues/14637
+TEST(RooFitHS3, ScientificNotation)
+{
+   RooRealVar v1("v1","v1",1.0);
+   RooRealVar v2("v2","v2",1.0);
+
+   // make a formula that is some parameters times some numbers
+   auto thestring = "@0*0.2e-6 + @1*0.1";
+   RooArgList arglist;
+   arglist.add(v1);
+   arglist.add(v2);
+
+   RooFormulaVar fvBad("fvBad", "fvBad", thestring, arglist);
+
+   // make gaussian with mean as that formula
+   RooRealVar x("x","x",0.0,-5.0,5.0);
+   RooGaussian g("g","g",x, fvBad, 1.0);
+
+   RooWorkspace ws("ws");
+   ws.import(g);
+   //std::cout << (fvBad.expression()) << std::endl;
+
+   // export to json
+   RooJSONFactoryWSTool t(ws);
+   auto jsonStr = t.exportJSONtoString();
+
+   // try to import, before the fix, it threw RooJSONFactoryWSTool::DependencyMissingError because of problem reading the exponential char
+   RooWorkspace newws("newws");
+   RooJSONFactoryWSTool t2(newws);
+   ASSERT_TRUE(t2.importJSONfromString(jsonStr));
+}