  With this paper we bring about a discussion on the computing potential of
complex optical networks and provide experimental demonstration that an optical
fiber network can be used as an analog processor to calculate matrix inversion.
A 3x3 matrix is inverted as a proof-of-concept demonstration using a fiber
network containing three nodes and operating at telecomm wavelength. For an NxN
matrix, the overall solving time (including setting time of the matrix elements
and calculation time of inversion) scales as O(N^2), whereas matrix inversion
by most advanced computer algorithms requires ~O(N^2.37) computational time.
For well-conditioned matrices, the error of the inversion performed optically
is found to be less than 3%, limited by the accuracy of measurement equipment.
