Let A be an n x n complex matrix. Then the numerical range of A, W(A),
is defined to be {xAx : x is an element of C-n, x*x = 1}. In this ar
ticle a series of tests is given, allowing one to determine the shape
of W(A) for 3 x 3 matrices. Reconstruction of A, up to unitary similar
ity, from W(A) is also examined. (C) Elsevier Science Inc., 1997