Lower/Upper Triangular Matrix

Construct a matrix with ones at and below the given diagonal and zeros elsewhere.

Usage

tri(nrow, ncol = nrow, k = 0, diag = TRUE)

Arguments

nrow

The desired number of rows.

ncol

The desired number of columns.

k

The sub-diagonal at and below which the matrix is filled. k = 0 is the main diagonal, while k < 0 is below it, and k > 0 is above. The default is 0.

diag

Logical indicating whether to include the diagonal. Default is TRUE.

Examples

tri(5, 5)
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    1    0    0    0    0
#> [2,]    1    1    0    0    0
#> [3,]    1    1    1    0    0
#> [4,]    1    1    1    1    0
#> [5,]    1    1    1    1    1
tri(5, 5, 2)
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    1    1    1    0    0
#> [2,]    1    1    1    1    0
#> [3,]    1    1    1    1    1
#> [4,]    1    1    1    1    1
#> [5,]    1    1    1    1    1
tri(5, 5, -1)
#>      [,1] [,2] [,3] [,4] [,5]
#> [1,]    0    0    0    0    0
#> [2,]    1    0    0    0    0
#> [3,]    1    1    0    0    0
#> [4,]    1    1    1    0    0
#> [5,]    1    1    1    1    0