Method and apparatus for minimizing a memory table for use with nonlinear monotonic arithmetic functions

摘要

A method which reduces the memory required to store correction factors used in logarithmic addition and subtraction of logarithmic operands. The method is implemented by a circuit which adds a predetermined correction factor to the minimum value of two logarithmic input operands. Correction factors are quantized to single polarity values. Predetermined ranges of magnitude values of the correction factors are selected in which the minimum value of each range is represented by a bias level. As a result of the bias levels, stored representations for the addition and subtraction factors are made much smaller resulting in less memory which is required. An addition of a predetermined bias level to the minimum value is effected simultaneous to addressing a predetermined adjustment factor in the reduced memory. A second addition is required to provide an output which represents either an addition or subtraction of the signed operands.