Paul Felix Neményi (June 5, 1895 – March 1, 1952) was a Hungarian mathematician and physicist who specialized in continuum mechanics. He was known for using what he called the inverse or semi-inverse approach, which applied vector field analysis, to obtain numerous exact solutions of the nonlinear equations of gas dynamics, many of them representing rotational flows of nonuniform total energy. His work applied geometrical solutions to fluid dynamics. In continuum mechanics, "Neményi's theorem" proves that, given any net of isothermal curves, there exists a five parameter family of plane stress systems for which these curves are stress trajectories.