'Transform parameters of the standardized model to the original model
Parameters
params : ndarray
parameters estimated with the standardized model
Returns
params_new : ndarray
parameters transformed to the parameterization of the original
model'

def transform_params(self, params):

    params_new = (params / self.scale)
    if (self.const_idx != 'nc'):
        params_new[self.const_idx] -= (params_new * self.mean).sum()
    return params_new
