lab_exer2.R

# Problem 1
f1 <- function(n, k){
  # initialize an nxn matrix with empty elements
  mat <- matrix(ncol = n, nrow = n)
  # evealuate the indices i and j
  for(i in 1:nrow(mat)){
    for(j in 1:ncol(mat)){
      # assign values
      mat[i, j] = if(i == j) k else if(j == i +1 || i == j + 1) 1 else 0
    }
  }
  return(mat)
}
# test inputs for prob 1
print(f1(10, 2))

# Problem 2
f2 <- function(a = a %% 360){
  return(floor((((if( a < 0) a + 360 else a)/90) %% 4) + 1))
}
# test inputs for prob 2
print(f2(45))
print(f2(90))
print(f2(180))
print(f2(270))
print(f2(360))

# Problem 3
f3 <- function(m){
  for(i in 1:nrow(m)){
    for(j in 1:ncol(m)){
      m[i,j] = if(m[i,j] %% 2 != 0) m[i,j]*2 else m[i,j]
    }
  }
  return(m)
}

# test inputs for prob 3
N <- matrix(c(c(1,5,-2),c(1,2,-1),c(3,6,-3)), ncol = 3, nrow = 3)
print(N)
print(f3(N))