[SOLVED] Multi Pt100 for Pic18 with unstable power

[OrdosDeviator]

Maybe someone find it useful.
If you have 3 dots and want to build quadratic formula, here is:
you have x1 y1 x2 y2 x3 y3, calculations on the picture will give you a b c
for equastion y=a*x*x+b*x+c

 

[c_mitra]

Maybe someone find it useful.
If you have 3 dots and want to build quadratic formula, here is:
you have x1 y1 x2 y2 x3 y3, calculations on the picture will give you a b c
for equastion y=a*x*x+b*x+c

This is not be recommended way.

You need to have several points (more than 3), say n, and you fit a quadratic equation using least square best fit method. You can use excel to find the coefficients. This gives the best result for the observed data point. Best results will come with 5-8 points in the interval of interest.