When an operator is called with a value from outside its domain, for example division by zero or a square root of a negative number, Rax will return a missing value and, in some cases, emit a warning. For example

`print sqrt:(-1); // Error: Function returning zero on domain error: sqrt:(-1 < [0,inf)). // Output: 0

Note that `sqrt:`

is a Rax built-in math
operator. For more about Rax's math library see
Chapter 17, *Math library*.