  A formulation of the Ginzburg-Landau-Wilson version of the partition function
of a system with a continuously varying order parameter as a transfer matrix
calculation allows for the application of methods based on the Density Matrix
Renormalization Group (DMRG) to the calculation of the free energy of the O(1)
model. The essence of both the mapping and the DMRG calculation is laid out,
along with results that validate this strategy. This method forms the basis of
a unified approach to the crossover from three to two dimensions in an O(1)
system with a slab-like geometry.
