Abstract: A hybrid analog and digital computational system is created by receiving equations in which a set of solution values is unknown. A residual iterative algorithm is implemented to solve the set of solution values for the equations. The residual iterative algorithm includes an outer update loop computed using a digital computing device with a set of residue values initially set to a first initial value and a set of solution update values set to a second initial value. The residual iterative algorithm includes an inner residual loop, which is iteratively computed using an analog accelerator until one or more inner residual loop stopping criteria is met and returning the set of solution update values. Next, the set of solution updates are used to update the set of residue values and a range of a next set of solution update values, thereby adjusting a computational precision of the inner residual loop.

Abstract: A tooth brush with replaceable bristles is disclosed. A brush head of the tooth brush includes a housing, a connection mechanism, a bristle part and a button. The connection mechanism is fixedly installed in the housing. The bristle part is detachably mounted to the connection mechanism. The button is movably mounted to the housing by the connection mechanism, and is capably to be pushed toward the bristle part to dismantle the bristle part from the connection mechanism. As such, by simply pushing the button, a convenient replacement of the bristles of the tooth brush is achieved.