Patent ID: 6711596
Filing Date: 2004-03-23
Classification: G06F

Abstract:
A logarithmic calculating apparatus for determining the approximate value of a logarithmic function F(x) at a value of x of interest, the apparatus comprising:first memory means for storing values of the function F(x) for a plurality of discrete values of x; second memory means for storing values of Fâ€²(x), the slope of the function F(x), for said plurality of discrete values of x; first multiplier means for multiplying the value of Fâ€²(x) for a said discrete value of x adjacent to the value of x of interest by &dgr;, the difference between said adjacent discrete value of x and the value of x of interest; third memory means for storing values of E(x), the approximate difference between {F(x)+&Dgr;Â·Fâ€²(x)} and F(x+&Dgr;) where x and x+&Dgr; are the adjacent pair of said discrete values of x nearest to the value of x of interest; fourth memory means for storing values of P(&dgr;), the ratio of (i) the difference between F(x+&dgr;) and {F(x)+&dgr;Â·Fâ€²(x)}, to (ii) E(x) for a plurality of values of &dgr;; second multiplier means for multiplying together the outputs of said third and fourth memory means; and adder means for adding together the outputs of said first memory means, said first multiplier means and said second multiplier means to produce an output representing the approximate value of F(x) at the value of x of interest.