V.Nagarajan,

Try using a higher order polynomial fit, I tried it in Excel, which allows a maximum of 6th order, and the R squared number = 0.999 which is close to a 0.1% full scale match. If you need an even closer fit, maybe Matlab can do higher than 6th order. Michael also brings up another method, piece-wise linear interpolation, which if the data points are close together, can be very accurate. This method will also allow you to use a lookup table and get a quick calculation, since the math for this method is simple.


Jacob