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(2) x(t) must have a finite number of max- ima and minima during a period, and (3) x(t) must have a finite number of (finite) discon- dirty bit a status bit used to indicate if a block (e.g., cache block, page, etc.) at some dirty page a page in memory that has been altered since last loaded into main memory. disable action that renders a device inca- pable of performing its function; the opposite disagreement of interests situation in which there are several decision units with disassembler a computer program that can take an executable image and convert it disc See Also spelled “disk.” DISC Cerenkov counter stands for dif- ferential isochronous self-collimating Cerenkov disco contraction of "distribution com- pany," a firm which owns the electric distri- disconnect switch a manually operated switching device used to disconnect circuit discontinuity effect an appropriate equiv- alent circuit model for discontinuities that discontinuity manifold See sliding discontinuous control the control law that is allowed to vary discontinuously to ac- u = −Usign(s(e)) , where e is a control error and s is a function of e, where sign (s) =
−1 if s < 0 1 if s > 0. discrete cosine transform (DCT) a popu- lar format for video compression. The spatial The forward 2-D DCT of an n × n block is defined as F (u, v) = 4 C(u)C(v) n 2 n−1 X j=0 n−1 X k=0 f (j, k) cos (2j + 1)uπ 2 n cos (2k + 1)vπ 2 n and the inverse is defined as f (j, k) = n−1 X j=0 n−1 X k=0 C(u)C(v)F (u, v) cos (2j + 1)uπ 2 n cos (2k + 1)vπ 2 n where C(w) = 1 √ 2 for w = 0 and 1 for w = 1, 2, . . . , n − 1. c 2000 by CRC Press LLC |