What I did was get the min/max range of the values and input them inside the gradient. Afterwards adjust the color dots so that they are in the middle of the range you described
I ended up finding this definition by Chris Hanley and tweaked something to make it work with my case. This way I can more dynamically change the bounds of each domain with sliders.
I took away the average component from the original def, added the absolute as Kim did, and then also added a formula to replace the infinite values from Tan(90) with a lower number.