Is triangular matrix

is_lower_triangular tests if a matrix is lower triangular
is_upper_triangular tests if a matrix is upper triangular
is_triangular_matrix tests if a matrix is triangular (both lower or upper triangular)

Arguments

x

a matrix

diag

should the diagonal be included? (FALSE by default)

Examples

some_matrix = matrix(1:9, 3, 3)
lower_matrix <- upper_matrix <- some_matrix
lower_matrix[upper.tri(some_matrix)] <- 0
upper_matrix[lower.tri(some_matrix)] <- 0

is_triangular_matrix(some_matrix) # TRUE
#> [1] FALSE
is_triangular_matrix(lower_matrix) # TRUE
#> [1] TRUE
is_triangular_matrix(upper_matrix) # TRUE
#> [1] TRUE

is_lower_triangular(some_matrix) # FALSE
#> [1] FALSE
is_lower_triangular(lower_matrix) # FALSE
#> [1] TRUE
is_lower_triangular(upper_matrix) # FALSE
#> [1] FALSE

is_upper_triangular(some_matrix) # FALSE
#> [1] FALSE
is_upper_triangular(lower_matrix) # FALSE
#> [1] FALSE
is_upper_triangular(upper_matrix) # FALSE
#> [1] TRUE