Lower the period following a display style fraction

Question

I dislike the look of the output of the following code because the period mark following the fraction looks confused (to my eyes, at least), almost like it's trying to be a degree symbol. I wish that it was sitting on the same (invisible horizontal) line that the denominators are sitting on, only I don't want it to be inside of the denominator (that is, I don't want to write $$\frac{S}{D} = \frac{x}{360.}$$ rather than $$\frac{S}{D} = \frac{x}{360}.$$), because that would awkwardly extend the fraction line above the period.

How can I place the period on the outside of the fraction such that it is at the same vertical level as the period in $$\frac{S}{D} = \frac{x}{360.}$$?

\documentclass{article}
\usepackage{amsmath}

\begin{document}

Suppose I have something like $$\frac{S}{D} = \frac{x}{360}.$$

\end{document}

(Note: A closely related question is raised at Vertical position of punctuation following fractions in display-style equations, but there is no talk there of dropping the period to the floor, which is what I want.)

Answer 1

I see nothing wrong in the second example (just normal punctuation), but also the third example may be appealing (thin space before the period).

I can see no reason for lowering the period, like in the first example: it's definitely out of place there.

\documentclass{article}
\usepackage{amsmath}

\newlength{\lowerpunct}
\newcommand{\finalfrac}[3]{%
  % #1 = numerator, #2 = denominator, #3 = punctuation
  \settodepth{\lowerpunct}{$\displaystyle\frac{#1}{#2}$}%
  \frac{#1}{#2}%
  \raisebox{-\lowerpunct}{#3}%
}

\begin{document}

Suppose I have something like
\[
\frac{S}{D} = \finalfrac{x}{360}{.}
\]

Suppose I have something like
\[
\frac{S}{D} = \frac{x}{360}.
\]

Suppose I have something like
\[
\frac{S}{D} = \frac{x}{360}\,.
\]

\end{document}