Abstract: A method is disclosed for characterizing a first data set of digital values and a second data set of digital values. The method includes determining a first similarity measure indicating a similarity of the digital values within the first data set; determining a second similarity measure indicating a similarity of the digital values within the second data set; determining a correlation value on the basis of the first data set and the second data set; and electronically outputting the correlation value, the first similarity measure and the second similarity measure.

Abstract: A compact assembly (40) with a turbine (20) fixed to a rotating drive shaft (22) with an extensible joint connected to small brush (38) by a shaft on the brush (36). The assembly (40) is inserted into a standard pool vacuum head (50) suction cavity (52) to provide a localized scrubbing action. The brush (38) is powered by the water pulled through the suction cavity (52) in the vacuum head (50) driving the turbine (20) causing rotation of the drive shaft (22) and brush shaft (36). The brush (38) is mounted to the end of the brush shaft (36). A spring (34) that is placed coaxial about the brush shaft (36) holds the brush (38) in contact with the surface (70) being scrubbed clean.