To find the index of the maximum element, you can use the **which.max()** function from the base package.

The basic syntax of which.max() is given below:

which.max(x)

Arguments:

**x **

numeric (logical, integer or double) vector or an R object for which the internal coercion to double works whose min or max is searched for.

In your case:

mat <- matrix(c(1:3,7:9,4:6), byrow = T, nc = 3)

which.max( mat[,2] )

[1] 2