R: Direct sum of two arrays

direct.sum {matrixcalc} | R Documentation

## Direct sum of two arrays

### Description

This function computes the direct sum of two arrays. The arrays can be numerical vectors or matrices. The result ia the block diagonal matrix.

### Usage

    direct.sum( x, y )

### Arguments

`x` | a numeric matrix or vector
`y` | a numeric matrix or vector

### Details

If either \bf{x} or y is a vector, it is converted to a matrix. The result is a block diagonal matrix ≤ft[ {\begin{array}{*{20}c} {\bf{x}} & {\bf{0}} \\ {\bf{0}} & {\bf{y}} \\ \end{array}} \right].

### Value

A numeric matrix.

### Author(s)

Frederick Novomestky fnovomes@poly.edu, Kurt Hornik Kurt.Hornik@wu-wien.ac.at

### References

Magnus, J. R. and H. Neudecker (1999) Matrix Differential Calculus with Applications in Statistics and Econometrics, Second Edition, John Wiley.

### Examples

    x <- matrix( seq( 1, 4 ) )
    y <- matrix( seq( 5, 8 ) )
    print( direct.sum( x, y ) )

[Package matrixcalc version 1.0-3 Index]