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The output of maxfilter can be written to a text file (e.g. using the "tee" command in unix). For example, if you use movement compensation (-movecomp), this file will contain movement and HPI-fit parameters for each time step (usually every 200ms). We recommend you look at this output carefully, since it may help detect fundamental problems with HPI positioning, or whether your participant moved during a session. A possible Matlab script for reading the maxfilter output is shown below, together with a shorter script that reads the output and displays it in separate figures for each input file.

This script reads and displays info from maxfilter output file (if -movecomp was used):

% Files with maxfilter outputs, e.g. for different subjects and conditions
movecompfiles = {'outputfile1.log', ...
                 'outputfile2.log', ...
                 'outputfile3.log');

nr_files = length(movecompfiles);

for ff = 1:nr_files,
    
    [mv_fig, linet, linee, lineg, linev, liner, lined] = check_movecomp(movecompfiles{ff}); % read info from log-file
    [a,b,c,d] = fileparts( movecompfiles{ff} );
    tittxt = [a(end-17:end) '/' b]; % just one way to keep the figure title short
    figure( mv_fig );
    % check_movecomp only creates the figure, but without the title, so you can do this separately
    ht = title(tittxt); set(ht, 'interpreter', 'none'); % add title to figure

end;

The previous script uses the following Matlab function (also in /imaging/olaf/MEG/maxfilter):

function [mv_fig, linet, linee, lineg, linev, liner, lined] = check_movecomp(mvcomp_file);
% read and plot maxfilter output from log-file
% [mv_fig, linet, linee, lineg, linev, liner, lined] = check_movecomp(mvcomp_file);

colours = {'b', 'g', 'r', 'm', 'c', 'k', 'y'};

fprintf(1, 'Input file: %s.\n', mvcomp_file);

fid_in = fopen(mvcomp_file);    % open movecomp log-file

now_line = fgetl(fid_in);

cc = 0;
fprintf(1, 'Reading line ');
while feof(fid_in) == 0,     
    if ~isempty(deblank(now_line)),
        cc = cc + 1;
        alllines{cc} = now_line;
        if ~mod(cc,100), fprintf(1, '%d ', cc); end;
        if ~mod(cc,1000), fprintf(1, '\n', cc); end;
    end;
    now_line = fgetl(fid_in);
end;    % while...
nr_lines = cc;
fprintf(1, '\n%d lines read\n', nr_lines);

HPIline = 'Hpi fit OK, movements [mm/s]';
lenH = length(HPIline);

Tline = '#t =';
lenT = length(Tline);

c_fit = 0;
t_fit = 0;
for cc = 1:nr_lines,
    thisline = alllines{cc};
    n = length(thisline);
    
    if n>=lenH && strcmp(thisline(1:lenH),HPIline),
        c_fit = c_fit+1;
        [tmp, restof] = strtok(thisline, '=');
        [tmp, restof] = strtok(restof(2:end), '/');
        cnt=0;
        while ~isempty(deblank(restof)),            
            if length(find(findstr(tmp, '-')))==0,
                cnt=cnt+1;
                xyz(cnt,c_fit) = str2num(tmp);
            end;           
            [tmp, restof] = strtok(restof(2:end), '/');
        end;
    end;
    
    if n>=lenT && strcmp(thisline(1:lenT),Tline),
        t_fit = t_fit+1;
        
        [tmp, restof] = strtok(thisline, 't');
        [tmp, restof] = strtok(restof, '=');
        [tmp, restof] = strtok(restof, ',');
        linet(t_fit) = str2num( tmp(2:end) );
        
        [tmp, restof] = strtok(thisline, 'e');
        [tmp, restof] = strtok(restof, '=');
        [tmp, restof] = strtok(restof);
        [tmp, restof] = strtok(restof);
        linee(t_fit) = str2num( tmp(2:end) );
        
        [tmp, restof] = strtok(thisline, 'g');
        [tmp, restof] = strtok(restof, '=');
        [tmp, restof] = strtok(restof);
        [tmp, restof] = strtok(restof, ',');
        lineg(t_fit) = str2num( tmp(2:end) );
        
        [tmp, restof] = strtok(thisline, 'v');
        [tmp, restof] = strtok(restof, '=');
        [tmp, restof] = strtok(restof);
        [tmp, restof] = strtok(restof);
        linev(t_fit) = str2num( tmp(2:end) );
        
        [tmp, restof] = strtok(thisline, 'r');
        [tmp, restof] = strtok(restof, '=');
        [tmp, restof] = strtok(restof);
        [tmp, restof] = strtok(restof);
        liner(t_fit) = str2num( tmp(2:end) );
        
        [tmp, restof] = strtok(thisline, 'd');
        [tmp, restof] = strtok(restof, '=');
        [tmp, restof] = strtok(restof);
        [tmp, restof] = strtok(restof);
        lined(t_fit) = str2num( tmp(2:end) );
        
    end;
    
end;

mv_fig(1) = figure;
subplot(2,1,1);
plot(linet, linee, colours{1}, linet, lineg, colours{2}, linet, linev, colours{3}, linet, liner, colours{4}, linet, lined, colours{5});
%legend( {'#e (cm)', '#g', '#v (cm/s)', '#r (rad/s)', '#d (cm)'} );
legend( {'fitting error (cm)', 'gof (0-1)', 'translation (cm/s)', 'rotation (rad/s)', 'drift (cm)'} );

if exist('xyz', 'var') && ~isempty(xyz),
    if size(xyz,2)~=length(linet),
        linet = 1:size(xyz,2);
        fprintf(1, '\n\nHPI problems!!! %s\n\n', mvcomp_file);
    end;
    subplot(2,1,2);
    plot(linet, xyz(1,:), colours{1}, linet, xyz(2,:), colours{2}, linet, xyz(3,:), colours{3});
    legend( {'x (mm/s)', 'y (mm/s)', 'z (mm/s)'} );
else,
    fprintf(1, '\n\nHPI problems!!! %s\n\n', mvcomp_file);
end;

attachment:fig_example.jpg