i am not understanding why you need an n-dimensional lookup table but the thing you can do is to proveide trend line for your data, eg
x=[1 3 4 5 6 8 9] y=[9 9 8 5 3 4 4]
this will convert your output value to according to input value in the lookup table but if the input value less than 1 or greater than 9 will always gives the result 9 and 4 respectivley.
also try it.
x=[0 1 3 4 5 6 8 9 10] y=[6 9 8 5 3 4 5 6 7]
with allowing interpolation and extrapolation and using saturation block with your desire max and min value,may be you get your required result you want to do
