2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/185526The Dirac equation for an electron in an external electromagnetic field can be regarded as a singular set of linear equations for the vector potential. Radford's method of algebraically solving for the vector potential is reviewed, with attention to the additional constraints arising from non-maximality of the rank. The extension of the method to general spacetimes is illustrated by examples in diverse dimensions with both $c$- and $a$-number wavefunctions.14 pages, LaTeXHigh Energy Physics - TheoryMathematical Physicstext