How can I write lightweight cross correlation code for arduino? I couldnt find any solution. The measurement system contains an ultrasonic sensor and a servo that turns from 45 to 135 degree and measures distance from 4-300 cm. Than i collect data in an array which contains distances with respect to angle. System makes several measurement like this and program finds cross correlation between new and old arrays.

http://www.instructables.com/id/How-To-Make-an-Obstacle-Avoiding-Arduino-Robot/