This is about mathematical terminology in English.
A simple curving line can have a top peak and a bottom valley. What is the correct term to use for the top/bottom point?
In my native tongue, we call it a toppunkt, literally meaning top-most point (although it counts for both peaks and valleys). When looking it up I have found the word vertex, which Wikipedia agrees with. Is this really the correct term?
Oxford Dictionaries doesn't seem to agree but only defines vertex as opposite angular points in a geometrical shape.
Vertex literally means turning point in Latin, so it does make sense. But from simple google searches, the word vertex doesn't seem to be used very often and the term turning point actually seems to be used as well.
I would appreciate help with sorting out the terminology here.
Note that I am aware that such a point is called a stationary point in 2D (and higher dimensions). I am specifically asking to the 1D case, though, where there is a special term.
Best Answer
This is quite technical mathematical language, the vertex, or apex is the point at which the curvature is a minimum or a maximum. For a vertical parbola, the vertex occurs at the maximum point. For a car driver, the apex of a turn is the point at which the steering wheel is turned the most.
However, it is more common to speak of
"Turning point" is the most useful term for the top or bottom of a curve.