In mathematical terms, the neuron fires if and only if; the
addition of input weights and of the threshold makes this neuron
a very flexible and powerful one. The MCP neuron has the ability
to adapt to a particular situation by changing its weights and/or
threshold. Various algorithms exist that cause the neuron to
'adapt'; the most used ones are the Delta rule and the back error
propagation. The former is used in feed-forward networks and the
latter in feedback networks.