```
form <- y ~ a + b + c
as.character(form) ## length 3
deparse(form) ## like the input
a0 <- 11/999 # has a repeating decimal representation
(a1 <- as.character(a0))
format(a0, digits = 16) # shows one more digit
a2 <- as.numeric(a1)
a2 - a0 # normally around -1e-17
as.character(a2) # normally different from a1
print(c(a0, a2), digits = 16)
```

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