eter line can have up to 7 elements: 'name',
% initial_value, min_value, max_value, prior_mu, prior_sigma, and
% targetflag

%%
% The |model| structure holds information about the model. Minimally
% we need to set |ssfun| for the sum of squares function and the
% initial estimate of the error variance |sigma2|.

model.ssfun  = ssfun;
model.sigma2 = mse; % (initial) error variance from residuals of the lsq fit

%%
% If we want to sample the error variance sigma2 as an extra model
% parameter, we need to set 