Fast CORDIC algorithm for ATAN2 on the Arduino.
This library is a collection (under construction) of trigonometric functions, efficiently calculated with the COordinate Rotation DIgital Computer (CORDIC) algorithm. The function implemented here is the atan2sqrt function, which calculates the angle and radius (length) of the vector that points to (x,y). This function is very useful in DSP applications such as digital down conversion.
The CORDIC implementation of ATAN2 is up to twice as fast as the atan2 from the standard Arduino library. The CORDIC algorithm rotates a vector clockwise until it is aligned with the positive x-axis. In this implementation the length of the vector is retained and thus, the square-root of x^2^ + y^2^ is known and equals to the value of x after rotation.
An example sketch is provided for benchmarking the CORDIC routine(s).