Dear Mike,

Yes. The first thing that I did when I got the sensor data was to make the Excel chart to see the data trend. Looking at the almost straight line I suggested that we use a straight line fit and be done with it - but the client was insisting that they have an area of interest in the 30 to 60MM region ( where the curve sort of bends) and hence all this stuff.

I also did notice the accuracy with which Paul's equation fits in the data - for our application this kind of accuracy is good enough and would have straight away used it, had this project been PC based as in such an event the code will be in VB.

Thanks

Raghu