The bifurcation function for an elliptic boundary value problem is a vector
field B(omega) on R-d whose zeros an in a one-to-one correspondence with t
he solutions of the boundary value problem. Finite element approximations o
f the boundary value problem are shown to give rise to an approximate bifur
cation function B-h(omega), which is also a vector field on R-d. Estimates
of the difference B(omega) - B-h(omega) are derived, and methods for comput
ing B-h(omega) are discussed. (C) 2000 John Wiley & Sons, Inc.