This function creates the difference operator matrix `delta`

for
subtracting a matrix row from the other matrix rows.

## Arguments

- J
The number of matrix rows.

- i
The row number to which respect differences are computed.

## Value

A matrix with `J-1`

rows.

## Details

Given a matrix `x`

with `J`

rows, then `delta(i,J) %*% x`

computes differences with respect to row `i`

.

## Examples

```
J <- 2
x <- matrix(1, nrow = J, ncol = 2)
RprobitB:::delta(J, 1) %*% x
#> [,1] [,2]
#> [1,] 0 0
```