[petsc-dev] simplification of solvers that utilize KSPNASH STCG or GLTR

[Barry Smith]

   Todd,

    The TAO solvers that utilize KSPNASH STCG or GLTR have all this horribly 
redundant unneeded code 

      /* Solve the trust region subproblem */
      if (NTR_KSP_NASH == tr->ksp_type) {
        ierr = KSPNASHSetRadius(tao->ksp,tao->trust);CHKERRQ(ierr);
        ierr = KSPSolve(tao->ksp, tao->gradient, 
tao->stepdirection);CHKERRQ(ierr);
        ierr = KSPGetIterationNumber(tao->ksp,&its);CHKERRQ(ierr);
        tao->ksp_its+=its;
        tao->ksp_tot_its+=its;
        ierr = KSPNASHGetNormD(tao->ksp, &norm_d);CHKERRQ(ierr);
      } else if (NTR_KSP_STCG == tr->ksp_type) {
        ierr = KSPSTCGSetRadius(tao->ksp,tao->trust);CHKERRQ(ierr);
        ierr = KSPSolve(tao->ksp, tao->gradient, 
tao->stepdirection);CHKERRQ(ierr);
        ierr = KSPGetIterationNumber(tao->ksp,&its);CHKERRQ(ierr);
        tao->ksp_its+=its;
        tao->ksp_tot_its+=its;
        ierr = KSPSTCGGetNormD(tao->ksp, &norm_d);CHKERRQ(ierr);
      } else { /* NTR_KSP_GLTR */
        ierr = KSPGLTRSetRadius(tao->ksp,tao->trust);CHKERRQ(ierr);
        ierr = KSPSolve(tao->ksp, tao->gradient, 
tao->stepdirection);CHKERRQ(ierr);
        ierr = KSPGetIterationNumber(tao->ksp,&its);CHKERRQ(ierr);
        tao->ksp_its+=its;
        tao->ksp_tot_its+=its;
        ierr = KSPGLTRGetNormD(tao->ksp, &norm_d);CHKERRQ(ierr);
      }

This can be simplified a great deal by making the names 

KSPCGSetRadius(), KSPGGGetNormD() etc you only need to change the registration 
from 

  ierr = 
PetscObjectComposeFunction((PetscObject)ksp,"KSPNASHSetRadius_C",KSPNASHSetRadius_NASH);CHKERRQ(ierr);
  ierr = 
PetscObjectComposeFunction((PetscObject)ksp,"KSPNASHGetNormD_C",KSPNASHGetNormD_NASH);CHKERRQ(ierr);
  ierr = 
PetscObjectComposeFunction((PetscObject)ksp,"KSPNASHGetObjFcn_C",KSPNASHGetObjFcn_NASH);CHKERRQ(ierr);

to 


  ierr = 
PetscObjectComposeFunction((PetscObject)ksp,"KSPCGSetRadius_C",KSPCGSetRadius_NASH);CHKERRQ(ierr);
  ierr = 
PetscObjectComposeFunction((PetscObject)ksp,"KSPCGGetNormD_C",KSPCGGetNormD_NASH);CHKERRQ(ierr);
  ierr = 
PetscObjectComposeFunction((PetscObject)ksp,"KSPCGGetObjFcn_C",KSPCGGetObjFcn_NASH);CHKERRQ(ierr);

Is there any reason we shouldn't do this? Essentially these three KSPs are a 
special subclass of KSPCG that supports these additional methods.  Anything 
specific to an individual one like the Lanczo stuff still remains with it.

  Barry