The matrix direct sum of 
matrices constructs a block diagonal matrix from a set of square matrices, i.e.,
 |  |  | (1) |
 |  | ![[A_1 ; A_2 ; ... ; A_n].](http://mathworld.wolfram.com/images/equations/MatrixDirectSum/Inline7.svg) | (2) |
Matrix Direct Sum
See also
Block Diagonal Matrix, Kronecker SumExplore with Wolfram|Alpha
References
Ayres, F. Jr. Schaum's Outline of Theory and Problems of Matrices. New York: Schaum, pp. 13-14, 1962.Referenced on Wolfram|Alpha
Matrix Direct SumCite this as:
Weisstein, Eric W. "Matrix Direct Sum." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/MatrixDirectSum.html