linearfeedback

Linear Feedback is a term that can refer to several related concepts in various fields, primarily in control systems and computer science. In control systems, a linear feedback loop is a system where the output signal is fed back and combined with the input signal in a linear manner to regulate the system's behavior. This allows for error correction and stability. For example, a thermostat uses a feedback loop to maintain a set temperature. If the room gets too cold, the feedback signal indicates this deviation from the desired state, and the system responds by turning on the heating. The linearity aspect means that the relationships between input, output, and feedback are proportional.

In computer science, particularly in the context of pseudorandom number generation, a linear feedback shift register (LFSR) is a type of shift register whose input bit is a linear function of its previous state. LFSRs are widely used in digital systems for tasks like generating pseudorandom sequences, error correction coding, and cryptography. The "linear feedback" in an LFSR refers to the fact that the feedback is achieved through a linear operation, typically an XOR (exclusive OR) of some of the register's bits. The sequence generated by an LFSR is deterministic but appears random for many practical purposes. The length of the sequence before it repeats depends on the design of the LFSR, specifically the polynomial used to define the feedback.