According to Wikipedia:
a closed-form expression is a mathematical expression expressed using a finite number of standard operations
I'm not sure if the floor and ceiling functions are considered standard in many scenarios. Regardless, suppose I have an expression that uses a finite amount of standard operations and floor or ceiling functions, is that expression closed form?
As a computation, the floor and ceiling functions are definitely computable with an algorithm of finite steps.
For example, one could define the floor function as: $\lfloor x\rfloor=x-(x$ mod $1)$
Would that definition qualify as closed?