# Correct phrasing for describing a plot

I am describing a plot (in a figure in a thesis I am currently writing) as follows:

Figure of [names of some mathematical functions]. Function A is covered by Function B for x < 10. (...)

Is this correct?

Basically I want to describe that Function B has the same values for x < 10 compared to Function A. That is why Function B is only plotted for x >= 10.

• Let f,g be the functions such that f,g < 10 but g >= 10, is that what you want? - It seems like a piecewise function. Commented Jun 18, 2016 at 18:31

I can suggest that you use the verbs coincide and overlap. Consider:

As you can see, output (result) of the function A coincide (overlap) perfectly with the result of function B for input variables lower than 10.

You can also say:

The Figure illustrates the excellent agreement between the result of the function A and function B for input variables lower than 10.

• Would you not prefer the term image [of a function f] to output (result) of the function f; and input values, or simply inputs to input variables? Also, I would dispense with excellent in the second sentence. “Note: g's image coincides with f's for inputs less than 10.”
– user3395
Commented Jun 18, 2016 at 22:02
• @user2684291 "image of a function" sounds awkward to me as well as using apostrophe with functions. Commented Jun 19, 2016 at 7:01
• I've seen these terms quite often—I'm not sure why they'd sound awkward. I suppose, perhaps in scientific papers, they're not that commonly used or summat? You can google `image of a function`, and if f is a name of a function then “f's” corresponds to “of f”.
– user3395
Commented Jun 19, 2016 at 14:41