# Blossom (functional)

In numerical analysis, a blossom is a functional that can be applied to any polynomial, but is mostly used for Bézier and spline curves and surfaces.

The blossom of a polynomial ƒ, often denoted ${\displaystyle {\mathcal {B}}[f],}$ is completely characterised by the three properties:

• It is a symmetric function of its arguments:
${\displaystyle {\mathcal {B}}[f](u_{1},\dots ,u_{d})={\mathcal {B}}[f]{\big (}\pi (u_{1},\dots ,u_{d}){\big )},\,}$
(where π is any permutation of its arguments).
• It is affine in each of its arguments:
${\displaystyle {\mathcal {B}}[f](\alpha u+\beta v,\dots )=\alpha {\mathcal {B}}[f](u,\dots )+\beta {\mathcal {B}}[f](v,\dots ),{\text{ when }}\alpha +\beta =1.\,}$
• It satisfies the diagonal property:
${\displaystyle {\mathcal {B}}[f](u,\dots ,u)=f(u).\,}$