-inf likelihood in allowable regions of parameter space

[dflemin3]

-inf likelihood in allowable regions of parameter space

[dflemin3]

I've now included checks in the only place the loglikelihood function is called in the ApproxPosterior.run method. If the loglike function returns a NaN or inf, the code halts because this means that the user's forward model is throwing an error or behaving improperly. In general, the loglike function should never return a non-finite answer as it should only ever see parameters that are explicitly allowed by the prior. For example when selecting a new design point thetaT,

thetaT = ut.minimizeObjective(self.utility, self.y, self.gp,
                                              sampleFn=self.priorSample,
                                              priorFn=self._lnprior,
                                              bounds=bounds, **kwargs)

the user must provide a prior function, priorFn, that ensures that each selected point is valid.