Ceiling Function/Examples/Ceiling of -1.1

Theorem

 * $\left\lceil{-1 \cdotp 1}\right\rceil = -1$

where $\left\lceil{x}\right\rceil$ denotes the ceiling of $x$.

Proof
We have that:
 * $-2 < -1 \cdotp 1 \le -1$

Hence $-1$ is the ceiling of $-1 \cdotp 1$ by definition.

Also see

 * Floor of $1\cdotp 1$: $\left\lfloor{1 \cdotp 1}\right\rfloor = 1$
 * Floor of $-1\cdotp 1$: $\left\lfloor{-1 \cdotp 1}\right\rfloor = -2$