subtract a constant vector from each row in a matrix in r

Question

I have a matrix with 5 columns and 4 rows. I also have a vector with 3 columns. I want to subtract the values in the vector from columns 3,4 and 5 respectively at each row o

Answer 1

A simple solution:

b <- matrix(rep(1:20), nrow=4, ncol=5)
c <- c(5,6,7)

for(i in 1:nrow(b)) {
  b[i,3:5] <- b[i,3:5] - c
}