(linear algebra) A matrix in which the entries outside the main diagonal are all zero.

plural of diagonal matrix

(category theory) A morphism from an object to the product of that object with itself, which morphism is induced by a pair of identity morphisms of the said object.

plural of diagonal mark

(typography) Synonym of slash as the forward slash ⟨/⟩ and sometimes also its proscribed sense inclusive of the backslash ⟨\⟩.

A proof, developed by Georg Cantor, to show that the set of real numbers is uncountably infinite.

A scale for laying down small fractions of the unit of measurement, the parallel lines drawn lengthwise on its surface being divided into sections by lines drawn crosswise, and in one end section being intersected by a series of other parallel lines drawn obliquely at equal distances across them.

plural of diagonal scale

plural of diagonal morphism

(linear algebra) Alternative spelling of antidiagonal.