Logarithmic Number System (LNS) is an alternative beside Floating Point (FLP) when an application requires a large dynamic range in the number processed. It allows simple implementation of multiplication and division using a Fixed Point (FXP) method without rounding error. In contrast, LNS addition and subtraction become more complex procedure. Therefore over the year, difference ways of improving the addition and subtraction function have been purposed. In this paper several techniques have been discussed and analysed such as direct lookup table, interpolation, table partitioning and co-transformation for approximating LNS addition and subtraction.
