In mathematics, a coefficient is a multiplicative factor that belongs to a certain object such as a variable, a basis vector, a basis function and so on. Usually, the objects and the coefficients are indexed in the same way, leading to expressions such as
- a_{1}x_{1} + a_{2}x_{2} + a_{3}x_{3} + …
Another meaning of coefficient is that of an important number that characterizes some property of a technical or scientific object.