The logarithmic and anti-logarithmic converters are realized with the piecewise linear approximation method, which is implemented by the shift-and-add architecture. This brief utilizes the similarities of Log and Antilog functions so that the adder tree block and multiplexer block can be shared by the Log and Antilog converters. As a result, the Antilog function can be implemented by the Log converter at the cost of additional 14% area and 6% latency. It implies the shift-and-add architecture can approximate multiple similar nonlinear functions with a slightly hardware cost. In addition, this brief proposes a set of formulas to predict the area and latency of shift-and-add architecture with different quantized coefficients that can facilitate the finding of a trade-off point in the Latency-Area-Precision space.