Mixed formulation of magnetodynamics in R/sup 3/. A posteriori errors

We present a mixed formulation of magnetodynamics where both electrical and magnetic fields are the unknown quantities. The two fields are simultaneously calculated by our code with the same accuracy as that of the field of a one field formulation and in about the same CPU time. As Ampere's law and Faraday's law are written in a weak form, the precision with which they are verified permits an a posteriori error calculus, giving criteria for adaptation of meshes.