Hallo Morgan Thank you for the clear reaction Sorry I missed your factor 1/2. I prefer to use names like mu and sigma, because they are widely agreed upon. I took a look to the log normal distribution and found it interesting. Maybe you appreciate this: Log_Normal_-1_-1 { ; Jos Hendriks ,2002 reset=2000 type=formula formulafile=fractint.frm formulaname=lognormal_distm passes=1 center-mag=0.169752/-0.0312433/0.1751883 params=-1/-1/0/0 float=y colors=000<2>00z<2>0zzzzezz0<2>z00e00L00zzLzL0000<2>00z<2>0zzzzezz0<2>z0\ 0e00L00zzLzL0000<2>00z<2>0zzzzezz0<2>z00e00L00zzLzL0000<2>00z<2>0zzzzezz\ 0<2>z00e00L00zzLzL0000<2>00z<2>0zzzzezz0<2>z00e00L00zzLzL0000<2>00z<2>0z\ zzzezz0<2>z00e00L00zzLzL0000<2>00z<2>0zzzzezz0<2>z00e00L00zzLzL0000<2>00\ z<2>0zzzzezz0<2>z00e00L00zzLzL0000<2>00z<2>0zzzzezz0<2>z00e00L00zzLzL000\ 0<2>00z<2>0zzzzezz0<2>z00e00L00zzLzL0000<2>00z<2>0zzzzezz0<2>z00e00L00zz\ LzL0000<2>00z<2>0zzzzezz0<2>z00e00L00zzLzL0000<2>00z<2>0zzzzezz0<2>z00e0\ 0L00zzLzL0000<2>00z<2>0zzzzezz0<2>z00e00L00zzLzL0zL0ccc<29>ccc } Much greetings