Abstract: A multi-function calculator suitable for a neural network architecture is provided. The multi-function calculator includes a plurality of activation function operation circuits and a demultiplexer (DMUX). The plurality of activation function operation circuits are configured to execute a plurality of different activation functions on an input signal respectively. The DMUX is coupled to the plurality of activation function operation circuits. The DMUX is configured to receive an enable signal and a selection signal. The DMUX in an enabled state selects one of the plurality of activation function operation circuits to be enabled according to the selection signal. The enabled activation function operation circuit executes a corresponding activation function on the input signal to generate a corresponding output signal.