The calculation of the S matrix is represented by a set of graphs, in which directed lines represent electrons and undirected dotted lines represent photons or interactions with a given electromagnetic field.
Ang pagkalkula ng S matris ay kinakatawan ng isang set ng mga graphs, na kung saan Directed linya ay kumakatawan sa mga electron at undirected may tuldok o linya ay kumakatawan sa photons ugnayan sa isang binigay na electromagnetic field.