MarkT:
float Twet= A*Tdry + B*rh + C*Tdry*Tdry + D*rh*rh+ E*Tdry*rh + F ;
Excellent, now I just to learn how to put the values of a-f into some sort of variable so this function can read them.
Cheers, and thanks for all your helps far. I am a newbie when it comes to C and more so when it comes to arduino.
M