___Dear all,
I am trying to solve a set of equations and I am using the “ROOT::Math::MultiRootFinder”
But I am not sure about the final output.
I wrote the following script
ROOT::Math::MultiRootFinder* r = new ROOT::Math::MultiRootFinder();
double R_Au = 5.46698; //N_activation per atom per sec (Nact/N0/ta/sigma0) 6.74002
double R_Cr = 5.36218; //N_activation per atom per sec (Nact/N0/ta/sigma0) 5.40852
double R_Co = 5.36700; //N_activation per atom per sec (Nact/N0/ta/sigma0) 5.38338
double R_Mo = 5.51876; //N_activation per atom per sec (Nact/N0/ta/sigma0) 5.03949
auto f_Au = [R_Au](const double * x)
{ return R_Au-x[1]-((15.47/pow(5.7,x[0]))+(0.429/(1+2*x[0])/(pow(0.55,x[0]))))*x[2];};
auto f_Cr = [R_Cr](const double * x)
{ return R_Cr-x[1]-((0.04/pow(7530,x[0]))+(0.429/(1+2*x[0])/(pow(0.55,x[0]))))*x[2];};
auto f_Co = [R_Co](const double * x)
{ return R_Co-x[1]-((1.61/pow(163,x[0]))+(0.429/(1+2*x[0])/(pow(0.55,x[0]))))*x[2];};
auto f_Mo = [R_Mo](const double * x)
{ return R_Mo-x[1]-((52.67/pow(241,x[0]))+(0.429/(1+2*x[0])/(pow(0.55,x[0]))))*x[2];};
r->AddFunction(f_Au,3);
r->AddFunction(f_Cr,3);
r->AddFunction(f_Co,3);
// r->AddFunction(f_Mo,3);
// starting point
double x0[3]={0.18, 5.36, 0.0069};
int printlevel = 1;
r->SetPrintLevel(printlevel);
r->Solve(x0);
the output are not accurate (x[0] = 0.240702 x[1] = 5.35869 x[2] = 0.0103042 ) compare to the initial value (They should be the correct results) .
In addition if I only changed the value of R_Au to 5.74002 the iteration does not approch to a solution.
Id there more accurate root finder with uncertainty value.
Thanks