correction term

A correction term is a type of modification to a formula (e.g., to one side of an equation) to handle (generally, to approximate) effects that a simplified formula does not handle. Many physical phenomena are most-fully described by equations so complicated as to be intractable. Some can be handled by a simplified equation that ignores various effects, the simplified equation often quite useful within a certain regime. In some cases, the simple equation can handle a larger regime with reasonable accuracy when a simple adjustment is made in the form of a correction term, a formula that approximates the difference between the simple formula and the more complicated formula that is being approximated. The correction term typically consists of a mathematical approximation, a mathematical function yielding a curve close to the actual difference to be approximated, e.g., a polynomial constructed to yield a similar curve. Many phenomena are commonly handled in such fashion within astrophysics: among the common are general relativity (e.g., with a post-Newtonian formalism) and the effects of magnetism.

If the modification is an additional factor, the term correction factor is sometimes used, but correction term is likely sometimes used as well (some equations are just as easily cited as a sum of terms rather than a product of factors, by using the log of each side).