k

See kilo-.

K

n. An old-style prefix or suffix meaning 1,024. As in, This system has 128KB of memory. See also binary prefixes.

USAGE: We recommend against continued use of K, in favor of Ki.

k

(key-low-ohm) abbr. See kiloohm.

K&R

(kay and aar) 1. abbr. Brian Kernighan and Dennis Ritchie, authors of the classic book, The C Programming Language (Prentice-Hall, 1978). 2. N. A common nickname for the book, The C Programming Language.

K&R C

(K and R see) N. An early, pre-ANSI standard for the C programming language.

Kalman filter

n. A tool for estimating the states of a linear system. Of all possible filters, it is the one that minimizes the variance of the estimation error.

A Kalman filter estimates the states x of a linear dynamic system defined by the equations

where A, B, and C are known matrices; x _k is the state of the system (a vector of quantities, unavailable for measurement) at time k; u _k is the known input vector to the system; y _k is the measured output vector; and w _k and z _k are noise vectors.

The filter equations are

where Sw and Sz are the covariance matrices of w and z, K is the Kalman gain, and P is the variance of the estimation error.

Kalman filters are often used in control systems where some or all of the desired feedback parameters are not observable by the...