calc_R_prior

 R = calc_R_prior( inv_model, varargin )
 CALC_R_PRIOR: calculate regularization matrix R
   The image prior is matrix n_elem x ??? 
 
 calc_R_prior can be called as
    R_prior= calc_R_prior( inv_model, ... )

 and will call the function inv_model.R_prior
 parameters to R_prior should be passed in the field
 inv_model.R_prior_function_name.parameters

 R_prior      calculated regularization prior R
 inv_model    is an inv_model structure

0001 function R_prior = calc_R_prior( inv_model, varargin )
0002 % R = calc_R_prior( inv_model, varargin )
0003 % CALC_R_PRIOR: calculate regularization matrix R
0004 %   The image prior is matrix n_elem x ???
0005 %
0006 % calc_R_prior can be called as
0007 %    R_prior= calc_R_prior( inv_model, ... )
0008 %
0009 % and will call the function inv_model.R_prior
0010 % parameters to R_prior should be passed in the field
0011 % inv_model.R_prior_function_name.parameters
0012 %
0013 % R_prior      calculated regularization prior R
0014 % inv_model    is an inv_model structure
0015 
0016 % (C) 2005-2008 Andy Adler. License: GPL version 2 or version 3
0017 % $Id: calc_R_prior.html 2819 2011-09-07 16:43:11Z aadler $
0018 
0019 if isfield(inv_model,'rec_model');
0020    inv_model.fwd_model= inv_model.rec_model;
0021    inv_model= rmfield(inv_model,'rec_model');
0022 end
0023 
0024 R_prior = eidors_obj('get-cache', inv_model, 'R_prior');
0025 if ~isempty(R_prior)
0026    eidors_msg('calc_R_prior: using cached value', 3);
0027    return
0028 end
0029 
0030 if isfield(inv_model,'R_prior')
0031    R_prior= feval( inv_model.R_prior, inv_model );
0032 elseif isfield(inv_model,'RtR_prior')
0033    % The user has provided an RtR prior. We can use this to
0034    % get R =RtR^(1/2). Not that this is non unique
0035    RtR_prior= feval( inv_model.RtR_prior, inv_model );
0036 
0037    % chol generates an error for rank deficient RtR_prior
0038    %     R_prior = chol (RtR_prior);
0039    % Instead we calculate cholinc with a droptol of 1e-5.
0040    %  For priors, this should be fine, since exact values
0041    %  especially far away, are not necessary
0042    ver = eidors_obj('interpreter_version');
0043    opts.droptol = 1e-5; 
0044    
0045    if ver.isoctave  || ver.ver < 7.012
0046       R_prior = cholinc(RtR_prior,opts.droptol);
0047    else
0048       R_prior = ichol(RtR_prior);
0049    end
0050 else
0051    error('calc_R_prior: neither R_prior or RtR_prior func provided');
0052 end
0053 
0054 if isfield(inv_model.fwd_model,'coarse2fine')
0055    c2f= inv_model.fwd_model.coarse2fine;
0056    if size(R_prior,1)==size(c2f,1)
0057 %     we need to take into account coarse2fine - using a reasonable tol
0058       R_prior=R_prior*c2f;
0059    end
0060 end
0061 
0062 eidors_obj('set-cache', inv_model, 'R_prior', R_prior);
0063 eidors_msg('calc_R_prior: setting cached value', 3);