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.
The distance formula is used to determine the distance, d, between two points. If the coordinates of the two points are (x 1, y 1) and (x 2, y 2), the distance equals the square root of x 2 â x 1 squared + y 2 â y 1 squared. The distance formula is derived by creating a triangle and using the Pythagorean theorem to find the length of the hypotenuse. The hypotenuse of the triangle is the distance between the two points.