I don't know but if I had to do it with analog I might simply do averaging. This will produce a spline approximation:
for example:
75 3.27 100 3.75if your input was 80 then your output is (3.75 - 3.27)/(100-75)*(80 - 75) +
3.27. i.e., fitting a line between the two points.now, you implement the analog electronics to compute that equation then use a multiplexer to select the different data points which is simply setup by using appropriate resistors that feed your analog equation calculator.
For a large number of data points this is out of the equation as also if linear approximation is bad. (you can use better approximations but the analog circuitry starts to get very complex real quick)
You gotta decide when the analog method starts to become more complex than a uC. Alsoa uC will, in general, be much more accurate and be easily changed even after fab.