diagX {sfsmisc}

The “Other” Diagonal Matrix

Description

Compute the other diagonal identity matrix. The result is basically a fast version of diag(n)[, n:1].

Usage

diagX(n)

Arguments

n

positive integer.

Value

a numeric n \times n matrix with many zeros – apart from 1s in the other diagonal.

Author(s)

Martin Maechler, 1992.

See Also

diag.

Examples

diagX(4)
for(m in 1:5)
  stopifnot(identical(diagX(m), diag(m)[, m:1, drop = FALSE]))