Part of this problem is underconstrained requirements. If you do not specify that “a” can’t be zero in “ax2”, it’s reasonable to behave sensibly in that case. O

Part of this problem is underconstrained requirements. If you do not specify that “a” can’t be zero in “ax2”, it’s reasonable to behave sensibly in that case. One thing is a free designer who states requirements and constraints. Another is an implementer who was given an isolated task and no more details. You have to be either full-defensive or renegotiate edge cases which probably could lead to unnecessary complexity.