## 3.3 Special Values

real not_a_number()
Not-a-number, a special non-finite real value returned to signal an error

real positive_infinity()
Positive infinity, a special non-finite real value larger than all finite numbers

real negative_infinity()
Negative infinity, a special non-finite real value smaller than all finite numbers

real machine_precision()
The smallest number $$x$$ such that $$(x + 1) \neq 1$$ in floating-point arithmetic on the current hardware platform