code: def eval_objfn(self):
          
  
          dfd = self.obfn_dfd()
          prj = sp.proj_l1(self.obfn_gvar(), self.gamma, axis=0)
          cns = np.linalg.norm(prj - self.obfn_gvar())
          return (dfd, cns)
docs: Compute components of regularisation function as well as total
          contribution to objective function.