```
A <- matrix(c(1, 2, 3, 1, 3, 2, 3, 2, 1), 3, 3, byrow = TRUE)
rref(A)
# [,1] [,2] [,3]
# [1,] 1 0 0
# [2,] 0 1 0
# [3,] 0 0 1
A <- matrix(data=c(1, 2, 3, 2, 5, 9, 5, 7, 8,20, 100, 200),
nrow=3, ncol=4, byrow=FALSE)
rref(A)
# 1 0 0 120
# 0 1 0 0
# 0 0 1 -20
# Use rref on a rank-deficient magic square:
A = magic(4)
R = rref(A)
zapsmall(R)
# 1 0 0 1
# 0 1 0 3
# 0 0 1 -3
# 0 0 0 0
```

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