In this letter we propose to use an extension of the variational approach
known as Truncated Conformal Space to compute numerically the Vacuum
Expectation Values of the operators of a conformal field theory perturbed by a
relevant operator. As an example we estimate the VEV's of all (UV regular)
primary operators of the Ising model and of some of the Tricritical Ising Model
conformal field theories when perturbed by any choice of the relevant primary
operators. We compare our results with some other independent predictions.Comment: LaTeX file, 11 pages. Revised Versio