To add noise to a simulated pattern (e.g. use the “simulate pattern from cif” command in jEdit menus you can use the function Rand_Normal(Mean, Std_Deviation); for example:

   xdd_out FILE load out_record out_fmt out_eqn
   {
       " %11.6f " = X;
       " %11.6f\n" = Rand_Normal(Ycalc, Sqrt(Ycalc));
   }

To test Rand_Normal then try:

iters 0
yobs_eqn = 100;
        min 0.001
        max 100
        del .001
 
   xdd_out aac.txt load out_record out_fmt out_eqn
   {
       " %11.6f\n" = Abs(Rand_Normal(0, 1));
   }

The data in AAC.TXT should obey the following:

             Sqrt[ Sum(AAC.TXT)^2 / 100000 ] = 1