Access random engine from TRandomGen

ROOT
3

Hi,

I understand your use case. Unfortunately there is no way of getting the Engine directly from TRandomMixMax, but there is an easy workaround, given the fact that the Engine is a protected member of TRandomGen (i.e. TRandomMixMax).
The workaround is to create a derived class of TRandomGen as following:

struct Rng : public TRandomGen<ROOT::Math::MixMaxEngine<240,0>> { ROOT::Math::MixMaxEngine<240,0> & GetEngine() { return fEngine; } };

auto rng = new Rng();  
auto mixmaxEngine = rng->GetEngine();
gRandom = rng;

I will consider for the future versions to add this possibility directly in the TRandomGen classes.
Thank you for your feedback !

Best regards

Lorenzo