Mathematics. Dictionary

An angle that is greater than 90 degrees and less than 180 degrees.

A triangle one of whose angles is obtuse.

A polygon with eight sides and eight angles.

Any function whose value changes sign if the independent variable changes sign i.e. f(-x) = -f(x)

Any integer that produces a noninteger when divided by two.

An interval in the real number line which does not contain its supremum and infimum. If specified by a pair of real numbers, then it consists of all the points on the real line whose values lie strictly between those two real numbers.

Informally, a set such that the target point of a movement by a small amount in any direction from any point in the set is still in the set; exemplified by a full circle without its boundary.

A branch of functional analysis, being the study of linear operators on function spaces.

The sequence in which the various operations in a mathematical expression are to be evaluated.

An object containing exactly two elements in a fixed order, so that, when the elements are different, exchanging them gives a different object. Notation: (a, b) or \langle a, b\rangle.

A natural number used to denote position in a sequence.

An equation involving the derivatives of a function of only one independent variable.

Of a figure: having all its sides and angles equal.

The point at which the axes of a coordinate system intersect.

The set of all vectors which are orthogonal to a given set of vectors.

A square matrix whose columns, considered as vectors, are orthonormal to each other. This implies that the transpose of such a matrix is also its inverse.