def METHOD_NAME(self, np=None, nxi=None):
    """
    Set hot grid resolution. Usually, only one of the parameters needs to be
    specified; the other one can be deduced from the size of 'f_hot'.
    """
    if np is None and nxi is None:
        return
    if np is not None:
        self.hot_np = np
        self.hot_nxi = self.hot_npnxi / np
    if nxi is not None:
        self.hot_nxi = nxi
        if self.hot_np is None:
            self.hot_np = self.hot_npnxi / nxi
    if self.hot_np*self.hot_nxi != self.hot_npnxi:
        raise Exception("Invalid size of f_hot specified. np*nxi should be {}.".format(self.hot_npnxi))
    self.update_unknown_sizes()