Definition:Strictly Negative Real Function

Definition
Let $I$ be a real interval.

Let $f$ be a real function.

Then $f$ is strictly negative (on $I$) iff:
 * $\forall x \in I: f \left({x}\right) < 0$

Also known as
A strictly negative real function is also described as a negative real function, but this causes confusion with a non-positive real function and so this usage is to be avoided.

Also see

 * Definition:Negative Real Function


 * Definition:Positive Real Function
 * Definition:Strictly Positive Real Function