H = hilb(n)
The Hilbert matrix is a notable example of a poorly conditioned matrix . The elements of the Hilbert matrices are H(i,j) = 1/(i + j – 1).
Even the fourth-order Hilbert matrix shows signs of poor conditioning.
cond(hilb(4)) = 1.5514e+04
 Forsythe, G. E. and C. B. Moler, Computer Solution of Linear Algebraic Systems, Prentice-Hall, 1967, Chapter 19.