A flat-type input unit capable of outputting information regarding a position where a finger touches as coordinate data is provided in a casing of an input device. A second circuit includes a second multiplication module for multiplying a second row of the matrix by a second instance of the vector variable to generate a second product, and a second linear solver module for calculating an updated second element of the vector variable using the second product. The layer is optically distinguishable from a belt body. The surface layer has a thickness between 10 microns and 1 millimeter and a surface tension energy of 22 dynescm or less and a polar components of 5 dynes or less. A pair of L-shaped and edge strips of hook and loop fastening material are affixed to a first and second side of the sling trough.