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    "# exampleMultiRoot\n",
    "Example of using multiroot finder based on GSL algorithm.\n",
    "\n",
    "Find the root of Rosenbrock system of equations:\n",
    "f1(x,y) = a(1-x)\n",
    "f2(x,y) = b(y-x^2)\n",
    "with:\n",
    "a = 1, b=10\n",
    "\n",
    "The MultiRootFinder is based on GSL and it requires the MathMore library\n",
    "installed.\n",
    "\n",
    "Usage:\n",
    "\n",
    "```cpp\n",
    " >.x exampleMultiRoot.C()\n",
    "```\n",
    "\n",
    "or\n",
    "\n",
    "```cpp\n",
    ">.x exampleMultiRoot(algoname,printlevel)\n",
    "```\n",
    "\n",
    "where algoname is for an algorithm not using the derivatives:\n",
    " hybridS (default) , hybrid, dnewton, broyden\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "**Author:** Lorenzo Moneta  \n",
    "<i><small>This notebook tutorial was automatically generated with <a href= \"https://github.com/root-project/root/blob/master/documentation/doxygen/converttonotebook.py\">ROOTBOOK-izer</a> from the macro found in the ROOT repository  on Tuesday, May 19, 2026 at 08:24 PM.</small></i>"
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   "source": [
    "%%cpp -d\n",
    "#include \"RConfigure.h\"\n",
    "\n",
    "#ifdef R__HAS_MATHMORE\n",
    "#include \"Math/MultiRootFinder.h\"\n",
    "#else\n",
    "#error libMathMore is not available - cannot run this tutorial\n",
    "#endif\n",
    "#include \"Math/WrappedMultiTF1.h\"\n",
    "#include \"TF2.h\"\n",
    "#include \"TError.h\"\n",
    "\n",
    "\n",
    "using namespace ROOT::Math;"
   ]
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   "source": [
    " Arguments are defined. "
   ]
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   "source": [
    "const char * algo = nullptr;\n",
    "int printlevel = 1;"
   ]
  },
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   "source": [
    "ROOT::Math::MultiRootFinder r(algo);"
   ]
  },
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   "metadata": {},
   "source": [
    "defining the function\n",
    "use Rosenbrock functions"
   ]
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   "source": [
    "TF2 * f1 = new TF2(\"f1\",\"[0]*(1-x)+[1]*y\");\n",
    "TF2 * f2 = new TF2(\"f2\",\"[0]*(y-x*x)\");\n",
    "f1->SetParameters(1,0);\n",
    "f2->SetParameter(0,10);"
   ]
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   "metadata": {},
   "source": [
    "wrap the functions"
   ]
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   "source": [
    "ROOT::Math::WrappedMultiTF1 g1(*f1,2);\n",
    "ROOT::Math::WrappedMultiTF1 g2(*f2,2);\n",
    "r.AddFunction(g1);\n",
    "r.AddFunction(g2);\n",
    "r.SetPrintLevel(printlevel);"
   ]
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   "source": [
    "starting point"
   ]
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     "text": [
      "GSLMultiRootFinder::Solve:hybrids max iterations 100 and  tolerance 1e-06\n",
      "GSL Algorithm used is :  hybrids\n",
      "Number of iterations  =  19\n",
      "Root values     = x[0] =            1   x[1] =            1   \n",
      "Function values = f[0] =            0   f[1] = -6.17162e-11   \n"
     ]
    },
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Info in <ROOT::Math::GSLMultiRootFinder::Solve>: The iteration converged\n"
     ]
    }
   ],
   "source": [
    "double x0[2]={-1,-1};\n",
    "r.Solve(x0);"
   ]
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