       % clear memory
        clear all;
        
        % convert files
        disp('converting files') ;
        [timemat, posmat] = gdf2mat('particles.gdf', 'rfqparticles.mat', [], [], 'all') ;

        % report sizes
        disp(['size of time array: ' num2str(length(timemat), '%1.0f')]);
        disp(['size of position array: ' num2str(length(posmat), '%1.0f')]);
        
        % clear memory
        clear all;
        
        % compute trajectories
        disp('computing trajectories');
        [trajmat] = gdftrans('rfqparticles.mat', 'rfqtrajectories.mat') ;
        
        % end
        disp('conversion complete');