Equidistant Conic Projection equations (Mapping Toobox)?

Does anyone know what equations are used to transform the latitude and longitude to X, Y points on a map for the Equidistant Conic Projection (eqdconic)?

I am using the eqdconic projection for a map and equations from the literature (peer-reviewed journal) but I seem to have a consistent offset between values I calculate from the journal equations and the values I get from using a cursor and the map properties. (It is not a question of screen resorption). Any help would be greatly appreciated.