diff --git a/pre_simulation_TREPR.m b/pre_simulation_TREPR.m
index c7a882c..1f04a71 100644
--- a/pre_simulation_TREPR.m
+++ b/pre_simulation_TREPR.m
@@ -1,14 +1,15 @@
-function [Exp,Sys,params] = pre_simulation_TREPR(params)
+function [params] = pre_simulation_TREPR(params)
 %PRE_SIMULATION_TREPR allows manual fitting of parameters in GUI
 %
-%   Usage: [Exp,Sys,params] = PRE_SIMULATION_TREPR(params), where params is
+%   Usage: [params] = PRE_SIMULATION_TREPR(params), where params is
 %   a struct, created by the load_bruker/matlab function and preprocessed
 %   by NORMALIZE_DATA, at least.
 %
 %   The function will show a window with a plot of the normalized mean of
 %   maxima (calculated by NORMALIZE_DATA) and serveral input fields for
-%   different relevant paramters of TREPR fitting. By pressing "Apply" the
-%   simulation will be calculated and displayed.
+%   different relevant paramters of TREPR simulation.
+%   By pressing "Apply" the simulation will be calculated and displayed.
+%   The simulation parameters will be saved to the params struct.
 
 %% creating UI
 fig = figure;
@@ -287,6 +288,9 @@ uiwait(fig)
              bfield,spec_norm,'b','LineWidth',1.2)
         legend('experimental','simulation')
         axis tight
+        %write manual fit to params
+        params.Manual_Sys = Sys;
+        params.Triplett_pop = Exp.Temperature;
     end
 
     function PreSimDoneButtonPushed(src,event)