Field transformation and Monte Carlo simulations
  A new method to compute observables at many values of the parameters \lambda for a model with lattice action {\cal{S}}(\phi, \lambda) is described. After fixing a reference set \lambda^r of parameters, a single simulation is carried out by using a ``reference action'' {\cal{S}} (\phi^r, \lambda^r) to generate configurations of the field \phi^r. Then a suitable analytic transformation is performed from the configurations of \phi^r to the ones corresponding to the action {\cal{S}} (\phi, \lambda). Such a transformation allows to obtain the observables for values of the parameters \lambda close to \lambda^r. I present studies on the reliability of the algorithm in the case of the \phi^4 model in 2 dimensions. 
M. Pepe