mat.dirprod {dae} | R Documentation |

## Forms the direct product of two matrices

### Description

Form the direct product of the `m \times n`

`matrix`

**A** and the `p \times q`

`matrix`

**B**.
It is also called the Kroneker product and the right direct product.
It is defined to be the result of replacing each element of
**A**, `a_{ij}`

, with `a_{ij}\bold{B}`

.
The result `matrix`

is `mp \times nq`

.

The method employed uses the `rep`

function to form two
`mp \times nq`

matrices: (i) the direct
product of **A** and **J**, and (ii) the direct product of
**J** and **B**, where each **J** is a matrix of ones
whose dimensions are those required to produce an
`mp \times nq`

matrix. Then the
elementwise product of these two matrices is taken to yield the result.

### Usage

`mat.dirprod(A, B)`

### Arguments

`A` |
The left-hand |

`B` |
The right-hand |

### Value

An `mp \times nq`

`matrix`

.

### Author(s)

Chris Brien

### See Also

`matmult`

, `mat.dirprod`

### Examples

```
col.I <- mat.I(order=4)
row.I <- mat.I(order=28)
V <- mat.dirprod(col.I, row.I)
```

*dae*version 3.2.28 Index]