1. A neural processor, comprising calculation apparatus (11-15) for extracting a root Q of a data X, which root constitutes either a norm of data or a distance between data, wherein the calculation apparatus comprises a preliminary neuron device (30) having an output; at least one plurality of (B-1) neurons arranged in parallel for computing terms q.sub.i .times.B.sup.i expressing a serial development of the root Q in an arithmetic base B, where B, q, and i are integers; a two-input first neuron (NQ), having a first input coupled to the output of the preliminary neuron device; a three-input second neuron, having a first input coupled to the output of the preliminary neuron device; first delay means (RQ) for delaying a signal on an output of the first neuron, the first delay means having an output for providing, ultimately, the root Q, the output of the first delay means being recursively coupled to a second input of the first neuron, a first input of the preliminary neuron device, and to a second input of the second neuron; and second delay means (RR) for delaying a signal on an output of the second neuron and having a first input coupled with the output of the second neuron; an output for providing, ultimately, a remainder R, the output of the second delay means being recursively coupled to a third input of the second neuron and to a second input of the preliminary neuron device; and a second input for initializing the second delay means with the data X.