Example: The function  formula_7  or just  formula_8  is the specific constant function where the output value is  formula_9. The domain is all real numbers ℝ. The codomain is just {4}. Namely, "y"(0)=4, "y"(−2.7)=4, "y"(π)=4... No matter what value of "x" is input, the output is "4".