dVo_dT(R1,TdegC)=-(Vcc*R1*R25*(-B/(TdegC*T1+273*T1)-((-B*(273-T1)-TdegC*B)*T1)/(TdegC*T1+273*T1)^2)*e^((-B*(273-T1)-TdegC*B)/(TdegC*T1+273*T1)))/(R25*e^((-B*(273-T1)-TdegC*B)/(TdegC*T1+273*T1))+R1)^2
where:
R1 is the bottom resistor (thermistor on top)
Vcc is the power supply voltage,
R25 is the resistance of the thermistor at temperature T1 (usually at 25 deg C),
T1 is the temperature that R25 is measured at (T1 in temperature units of K),
B is the thermistor constant,
TdegC is the temperature of the thermistor.