Analog Input. In this example we use a variable resistor (a potentiometer or a photoresistor), we read its value using one analog input of an Arduino or Genuino board and we change the blink rate of the built-in LED accordingly. The resistor's analog value is read as a voltage because this is how the analog inputs work.
For the Haigis formula, the a0 constant moves the power prediction curve up, or down, in much the same way that the SRK/T A-constant. The a1 constant is tied to the measured anterior chamber depth and the a2 constant is tied to the measured axial length.
and T is temperature (in Kelvin), and Td is dew point temperature (also in Kelvin). So, if you know the temperature, you can solve for Es, and substitute the equation for E into the expression for relative humidity and solve for Td (dew point).here Td is dew point temperature (in degrees Celsius), T is observed temperature (in degrees Celsius), and RH is relative humidity (in percent). Apparently this relationship is fairly accurate for relative humidity values above 50%. More details can be found in the article: