This work presents an analytical characterization of the parametric dependence of variables of resistive circuits by few data samples. Cramer’s solution of a linear system is alternatively formulated here as a rational function of polynomials of the parameters under study. Coefficients for these polynomials are calculated from few measures of system variables and known parameters. Discontinuities induced by measurement noises are fixed by regularization methods. Results are shown for both circuit simulations and experimental measurements. Ongoing work includes the application of the proposed approach in the synthesis of systems.