HEX smearing is not implemented for HMC but does not fail

[martin-ueding]

HEX smearing seems to be implemented for the HMC, one can create a hmc input XML which includes HEX_FERM_STATE and the simulation runs. However, lib/actions/ferm/fermstates/hex_fermstate_w.h reveals missing parts:

/* Not implemneted   **/
virtual void deriv(P& F) const 
{
  START_CODE();

  END_CODE();
}

I had started a simulation with this assuming that if there was a key in the factory, it would be implemented. In order to prevent people from creating false results, I think one should throw some exception in the missing methods to make the program fail fast with an error message saying that HEX smearing is not supported currently.

Should I implement that?

[bjoo]

HI Martin, Yes, I think in the past there was an attempt to create the smearing, but as you note the force term was not implemented - only the actual operation. I think there was some preliminary study to compare with stout maybe? It was long ago.

We had to put in the stub function to satisfy the calss interface I am guessing. It is true that usually we have an error message there saying something like:

QDPIO::cerr << “Not implemented” << std::endl; QDP_abort(1);

Feel free to implement, or if you like, implement the smearing force recursion :) Although going by how we did this for stouting, it was a bit yucky (we had to break out of QDP++ and do our own explicit site looping).

Thanks and best wishes, B

On Jan 12, 2017, at 6:19 AM, Martin Ueding notifications@github.com wrote:

HEX smearing seems to be implemented for the HMC, one can create a hmc input XML which includes HEX_FERM_STATE and the simulation runs. However, lib/actions/ferm/fermstates/hex_fermstate_w.h reveals missing parts:

/* Not implemneted **/ virtual void deriv(P& F) const { START_CODE();

END_CODE(); }

I had started a simulation with this assuming that if there was a key in the factory, it would be implemented. In order to prevent people from creating false results, I think one should throw some exception in the missing methods to make the program fail fast with an error message saying that HEX smearing is not supported currently.

Should I implement that?

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Dr Balint Joo High Performance Computational Scientist Jefferson Lab 12000 Jefferson Ave, Suite 3, MS 12B2, Room F217, Newport News, VA 23606, USA Tel: +1-757-269-5339, Fax: +1-757-269-5427 email: bjoo@jlab.org

[martin-ueding]

I have implemented the exception. It seems the interest in HEX smearing has been as a simple performance benchmark against STOUT. Perhaps it will become part of my thesis, until then I will focus on other things.