Sensor Linearization

[peter paul fenske]

Hi Folks:
Tnx to all lending me a hand.
Been looking through the archives but yet to find a proper discussion
on sensor linearization. 
The inclination is to accept the Map sensor data as well as the Tps
as they are linear even though there is a loss in range. 
One problem remaining is the MAT and the Coolant Temp Sensor.
Going by service manuals and using a 1.2 K pullup this gives quite
a nonlinear temp vs voltage.
The question I have for the good folks is how do you linearize the
sensor. Or is it necessary?
One tacky piece of hardware is to switch in two resistors one for 
each range which would tend to give some linearization.
Software wise one could use a lookup table. This would require close
to 255 entries. Not really but quite a few. The other way is a search
through a table and pick the data closest to the value measured.
And the third is to use a smaller table, say 15 values for a search
or a lookup and then interpolate. 
What I am trying to get is linear numbers between 0 and 255 for
a temp range of about -40 to 250 degrees.
Tnx again everybody: peter