In one-dimensional systems which consist of N nodes, the two N response matrix equations for the partial currents through the node interfaces have been transformed into a set of N three-point equations with the total in-current per node as the new variable. The resulting coefficients which describe the coupling between neighboring nodes are expressed in terms of the reflection and transmission matrices of the invariant imbedding theory. These coupling coefficients can be compared with those of other nodal equations. In the case of slab geometry this has been illustrated by a direct comparison with the familiar finite difference formulation with the average flux per node as the dependent variable. Also the relation between the method presented here and the so-called rigorous finite difference equations has been established. The advantage of this method lies in the fact that the flexibility of the response matrix methods—which describe the nodes in terms of invariant imbedding concepts—has been condensed into the conventional three-point finite difference scheme, for which many well-established solution methods exist.