#list is a new feature in v6. It's super-useful for running multiple refinements on different data sets or running multiple models against a single data set. Some things you can do are below. There are lots more!

Typical syntax is:

num_runs 5
Backup_INP
#list pa_val  {
0.1
0.2
0.3
0.4
0.5
}
prm pa = pa_val(Run_Number);

By default refinement results aren't written to the INP file. This can be changed with the lines below, where inp_filename.inp is the name of your INP file. Note that out_file uses a “string equation”. The “Backup_INP” macro creates a backup of your input file. This is useful as if you mess up with #list you can write a blank .inp file (essentially deleting your .inp).

Backup_INP
out_file ="inp_filename.inp";

If you step through a set of pa values and fit the data with each value Topas won't save the “best answer” by default. This can be changed with a simple macro:

macro Save_Best
   {
                #if (Run_Number == 0)
                                prm Best_Rwp_ = 9999;
                #else
                                prm Best_Rwp_ = #include Best_Rwp_.txt;
                #endif
                out Best_Rwp_.txt Out(If(Get(r_wp) < Best_Rwp_, Get(r_wp), Best_Rwp_))
                out_file = If(Get(r_wp) < Best_Rwp_, Concat(String(INP_File), ".OUT"), "");
   } 

You can easily automate refinements using the #list command and string equations. Just give the filenames in the #list command and use something like “xdd filename(Run_Number)”. You can add experimental information like time/temperature/etc in the #list command.

For results files you can e.g. delete old files and write header lines with commands like the ones below. If you backup only for run 0 then you won't get annoying screen “flashes”:

#if (Run_Number == 0)
 Backup_INP
 system_before_save_OUT  { del results.txt }
 out "results.txt" append 
 Out_String("     01_range   02_temp    03_time       04_r_wp     05_height    06_err     07_bval     08_err   09_perc_cubic  \n") 
#endif 

There's a step by step tutorial on using #list to refine a series of data sets sequentially here.

Here's an example of how to vary a specific parameter (the sample height) in the input file from Martin Fisch:

/*
Copy paste this file to an .inp file and run with Topas 6
It shows how the #list command can be used to perform pattern
simulations. In this case, specimen displacement is varied. 
Note that the list parameter (h_err) is used via a macro
in order to use it in the file name of the saved scan. 
*/
 
yobs_eqn = 0;
min 20
max 150
del 0.01
 
num_runs 11
 
#list h_err {
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
0.20
0.25
}
 
macro displacement { h_err(Run_Number) }
 
Specimen_Displacement(, displacement )
 
lam ymin_on_ymax 0.0001
Lam_recs
{ 0.0159  1.534753  3.6854
  0.5691  1.540596  0.4370
  0.0762  1.541058  0.6000
  0.2517  1.544410  0.5200
  0.0871  1.544721  0.6200 }
LP_Factor(0)
Rp 240
Rs 240
Slit_Width(0.07)
Divergence (0.25)
axial_conv
filament_length 12
sample_length 9.5
receiving_slit_length 15
primary_soller_angle 2.55
secondary_soller_angle 2.55
 
str
phase_name "LaB6"
a 4.1569162
b =Get(a);					
c =Get(a);					
space_group "Pm-3m"
site La1 x 0    y 0    z 0    occ La 1 beq 0.5
site B1  x 0.5  y 0.5  z 0.19 occ B  1 beq 0.5
scale 0.0001
 
seed 10
xdd_out LaB6_Displacement_##displacement##.xy load out_record out_fmt out_eqn
{
    " %11.6f  " = X;
    " %11.6f\n  " = Rand_Normal(Ycalc, Sqrt(Ycalc));
}

There's an example of how to name .out files by Run_Number at: Saving .out Files as a Function of Run Number