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.
Memorize the formula for the volume of a cylinder. To calculate the volume of a cylinder, you must know its height and the radius of the circular base (the distance from the center of the circle to its edge) at the top and bottom. The formula is V = Ïr2h, where V is the Volume, r is the radius of the circular base, h is the height, and Ï is the constant pi.