chilbyIts just a matter of how you think about those values
I need the stiffness range to be in the realm of/between 0.000001 and 1000000, as vellum usually goes...
You may ask yourself, which number is half way between those 2 numbers?
Is it 500000? Or is it 1?
What you'd get using attribremap is 500000 as that's linearly half way between those numbers
As well as in your picture your individual steps are roughly 787, so nothing wrong with the values you are getting
However you are expecting 1 to be in the middle since you are thinking about that range logarithmically as thats what they represent for stiffness, so in that case you need to also interpolate it logarithmically
So interpolate your exponent rather than the value itself
This is purely based on your screenshot values, which are a bit different from what you described, but you can adjust the exponents or source attrib or range as needed:
float exp = fit( @stiffness, 1.0078, 1.99906, -4, 5); f@stiffness = pow(10, exp);