VBA_fillInPriors.m

function [options,params2update] = VBA_fillInPriors(dim,options)
% fills in priors structure with default priors if necessary
% function [priors,params2update] = VBA_fillInPriors(priors,dim,verbose)
% IN: [see VBA_check.m]
%   - priors: [can be left empty]
%   - dim: [required]
%   - verbose: flag for verbose mode
% OUT:
%   - priors: complete priors structure
%   - params2update: for VBA inversion


% VBA default priors
default_priors = VBA_priors(dim,options);
if ~isfield(options,'priors')
    options.priors = struct();
end

% fill in VBA's priors structure with default priors
options.priors = check_struct(options.priors,default_priors);

% check dimension and infinite precision priors
if dim.n_theta > 0 % This finds which evolution params to update
    dpc = diag(options.priors.SigmaTheta);
    iz = find(dpc==0);
    params2update.theta = setdiff(1:dim.n_theta,iz);
else
    params2update.theta = [];
end
if dim.n_phi > 0 % This finds which observation params to update
    dpc = diag(options.priors.SigmaPhi);
    iz = find(dpc==0);
    params2update.phi = setdiff(1:dim.n_phi,iz);
else
    params2update.phi = [];
end
if dim.n > 0  % This finds which initial conditions to update
    dpc = diag(options.priors.SigmaX0);
    iz = find(dpc==0);
    params2update.x0 = setdiff(1:dim.n,iz);
    for t=1:dim.n_t
        dpc = diag(options.priors.iQx{t});
        iz = find(isinf(dpc));
        params2update.x{t} = setdiff(1:dim.n,iz);
    end
else
    params2update.x0 = [];
end