Viva delta marker

Hi,

For Viva delta markers the slope can displayed in the marker label using format [dx:%W] [dy:%H] [s:%S]. Instead of the slope I'd like to display 1/slope. On a long shot I tried [s:%1/S] and [s:%(1/S)] but no luck. 1/slope would be very useful to display considering it represents the resistance of a diode i-v curve. An even better feature would be the ability to specify an expression dependent on the dx,dy,x,y values.

Regards,

Brad