Calculates the sum for each row (column) in a matrix.
rowSums2(x, rows = NULL, cols = NULL, na.rm = FALSE, dim. = dim(x), ...)colSums2(x, rows = NULL, cols = NULL, na.rm = FALSE, dim. = dim(x), ...)
Not used.
The implementation of rowSums2() and colSums2() is
optimized for both speed and memory.