Sanakirja.org

Määritelmät

Substantiivi

1. A range; a continuous, infinite, one-dimensional set, possibly bounded by extremes.
2. Specifically, a range of colours representing light (electromagnetic radiation) of contiguous frequencies; hence electromagnetic spectrum, visible spectrum, ultraviolet spectrum, etc.
3. (psychology, education, usually with the) The autism spectrum.
4. (chemistry) The pattern of absorption or emission of radiation produced by a substance when subjected to energy (radiation, heat, electricity, etc.).
5. (mathematics, linear algebra) The set of eigenvalues of a matrix.
6. (mathematics, functional analysis) Of a bounded linear operator A, the set of scalar values λ such that the operator A—λI, where I denotes the identity operator, does not have a bounded inverse; intended as a generalisation of the linear algebra sense.
7. (commutative algebra, algebraic geometry) An abstract object in mathematics created from a commutative ring R and denoted \operatorname{Spec}(R) or \operatorname{Spec} R and said to be the spectrum of R; useful in the study of such rings for providing a geometric object which encodes many of the properties R, and in modern geometry for generalizing the notion of an algebraic variety to that of an affine scheme. Formally, the set of all prime ideals R equipped with the Zariski topology and augmented with a sheaf of rings called the structure sheaf, generated by the B-sheaf on the distinguished open sets D_f which assigns the localization of R at f to each set D_f, regarded as a ring of functions on D_f. See
8. (obsolete) Specter, apparition.
9. The image of something seen that persists after the eyes are closed.