Patent ID: 7171435

Claim:
A digital signal system for determining an approximate logarithm of a value of x having a base of b, comprising: circuitry for storing x as a digital representation; circuitry for identifying a most significant digit of the digital representation, wherein adjacent the most significant digit is located a set of bits in respective lesser significant bit locations; a table for storing a set of predetermined logarithms having the base of b, wherein each of the predetermined logarithms corresponds to a number in a set of numbers; circuitry for addressing the table in response to a first bit group of the set of bits in respective lesser significant bit locations, wherein in response the table is for outputting a one of the predetermined logarithms corresponding to a first number in the set of numbers; and circuitry for outputting the approximate logarithm of the value of x in response to the one of the predetermined logarithms and further in response to a function estimation between logarithms at a first and second endpoint, the first endpoint corresponding to the first number in the set of numbers times a power of b and the second endpoint corresponding to a second number in the set of numbers times the power of b, wherein the function estimation estimates a logarithm at a number located at distance from one of the first and second endpoints, wherein the distance is responsive to a second bit group of the set of bits.