Row/column counter in 'apply' functions

Question

What if one wants to apply a functon i.e. to each row of a matrix, but also wants to use as an argument for this function the number of that row. As an example,

Answer 1

What I usually do is to run sapply on the row numbers 1:nrow(test) instead of test, and use test[i,] inside the function:

t(sapply(1:nrow(test), function(i) test[i,]^(1/i)))

I am not sure this is really efficient, though.