Invert a dspNetwork knob value

[Morphoice]

I have a pre-gain and want to invert it's value to also apply it to a gain (so the overall level stays the same)
how do I douplicate and invert a knobs value in a dsp network?
cable_expr doesnt seem to work for simply negating it's input value

[d.healey]

@Morphoice Usual way to invert a knob is to subtract its value from the maximum value. So if you have a knob that goes from 0 to 100, you would subtract the knob's current value from 100. I don't know how you do this in scriptnode but I'm sure it will be possible.

[Morphoice]

@d-healey alright, I can do that in faust, no need for scriptnode then

[Christoph Hart]

@Morphoice use the xfader node.

[Morphoice]

@Christoph-Hart thanks