(linear algebra) A transformation matrix whose associated transformation is a projection.

(biochemistry) Any structural protein

(linear algebra) Matrix obtained by appending the columns of two given matrices, usually for the purpose of performing the same elementary row operations on each of the given matrices.

(linear algebra) A matrix consisting of the coefficients of the variables in a set of linear equations. The matrix is used in solving systems of linear equations.

(linear algebra) A square matrix which is obtained from the identity matrix by a single elementary row (or column) operation.

A simple diagram, equivalent to an adjacency matrix in graph theory, used to model the structure of complex systems or projects.

(mathematics) A special skew-symmetric 4×4 matrix that characterizes a straight line in projective space, and is defined by six Plücker coordinates with four degrees of freedom.

(algebra) Generically, the arithmetic of matrices, involving matrix addition, scalar multiplication of matrices, matrix multiplication, and matrix inversion.

(physics) Abbreviation of scattering matrix.

(grammar) A clause that has another (subordinate) clause embedded within it.