col(x) row(x)
NA
s) are allowed.
z[i,j]
is
i
for all
j
;
if z<-col(x),
z[i,j]
is
j
for all
i
.
Do not confuse this function with the
col
parameter in graphics functions;
see
par
for that use of
col
.
x[row(x)>col(x)] <- 0 # zero the strict lower triangle of x x[row(x)-col(x)==1] # first sub-diagonal