How to hide the dialog poping up when I do curve fitting?

I have a function to do exponent curve fitting in Z direction of every point in XY plane, but a dialog is flashing when fitting, that makes the procedure becomes slow. How can I make the dialog hidden and cure fitting faster?
If you are using Igor 6.21 you can add a /w=2 flag. This does not display the result window.
For ancient versions of Igor you can use a varaible calles V_fitOptions to control various options, Bit 2 suppresses the curve fit window.
For details:
displayhelptopic "Special Variables for Curve Fitting[V_FitOptions]"
A