将 \pgfmathprint 四舍五入到小数点后一位

Question

以下代码非常适合将每次构建的新输入/输出值打印为 PDF；但是，我无法将其四舍五入到小数位。它总是四舍五入到最接近的整数。我尝试过 \numprint 和 \sisetup 方法，但没有成功。这似乎是一个简单的问题；但是，我在这个论坛上部署类似问题的答案却没有成功。最终，我希望能够四舍五入到正确的数字，甚至尝试过使用“round-places”和“round-figures”来做到这一点，无论它们属于哪个包……都没有成功。

\documentclass[12pt]{article}
\usepackage{geometry}
\geometry{margin=1in}
\usepackage{pgf,amsmath,enumitem,siunitx}

\pgfmathsetseed{\number\pdfrandomseed} % seed for pseudo random generator

% new command to initialize variables
\newcommand\initVariables{%
    \pgfmathsetmacro{\A}{random(100,200)}%
    \pgfmathsetmacro{\B}{random(5,29)}%
}
% define command to calculate result
%\newcommand\answer{\pgfmathprint{round(\A / \B)}} 
\newcommand\answer{\pgfmathprint{round(\A / \B)}} 

\begin{document}
\begin{enumerate}

\initVariables % initialize variables   
    \item \textbf{An object is displaced \A \ meters in \B \ seconds.}\\ 
    \begin{equation*}
        v = \dfrac{\Delta s}{\Delta t} = \dfrac{\A \ m}{\B \ s} =
        \pgfmathparse{\A / \B}\pgfmathresult \ \frac{m}{s}
        \approx \answer \frac{m}{s}\\
    \end{equation*}

Answer 1

内核expl3对于浮点数有更好的管理。

宏\defineVariables（局部）设置变量应包含的内容。使用\initVariables表达式进行求值（因此实际上会替换随机整数）。

为了使用变量A，请使用\Var{A}（这比使用等更好\A，否则可能会重新定义重要的命令）。使用

\round(<expression>,<places>)

对表达式进行求值，并按规定的小数位数进行四舍五入。

\documentclass[12pt]{article}
\usepackage{geometry}
\geometry{margin=1in}
\usepackage{amsmath,enumitem,siunitx,xfp}


\ExplSyntaxOn
% no need to set the seed with expl3

% new command to initialize variables
\NewDocumentCommand{\defineVariables}{m}
 {
  \prop_set_from_keyval:Nn \l_clark_variables_def_prop { #1 }
 }
\NewDocumentCommand{\initVariables}{}
 {
  \prop_map_inline:Nn \l_clark_variables_def_prop
   {
    \prop_put:Nnx \l_clark_variables_set_prop { ##1 } { \fp_eval:n { ##2 } }
   }
 }
\NewExpandableDocumentCommand{\Var}{m}
 {
  \prop_item:Nn \l_clark_variables_set_prop { #1 }
 }
\NewExpandableDocumentCommand{\round}{mm}
 {
  \fp_eval:n { round(#1,#2) }
 }
\prop_new:N \l_clark_variables_def_prop
\prop_new:N \l_clark_variables_set_prop
\ExplSyntaxOff

\begin{document}

\begin{enumerate}
\defineVariables{
  A={randint(100,200)},
  B={randint(5,29)},
}
\sisetup{per-mode=fraction}
% initialize variables   
\initVariables
\item \textbf{An object is displaced \Var{A} meters in \Var{B} seconds.}
  \begin{equation*}
  v = \frac{\Delta s}{\Delta t}
    = \dfrac{\SI{\Var{A}}{m}}{\SI{\Var{B}}{s}}
    = \SI{\round{\Var{A}/\Var{B}}{5}}{\meter\per\second}
    \approx \SI{\round{\Var{A}/\Var{B}}{1}}{\meter\per\second}
  \end{equation*}

% initialize variables   
\initVariables
\item \textbf{An object is displaced \Var{A} meters in \Var{B} seconds.}
  \begin{equation*}
  v = \frac{\Delta s}{\Delta t}
    = \dfrac{\SI{\Var{A}}{m}}{\SI{\Var{B}}{s}}
    = \SI{\round{\Var{A}/\Var{B}}{5}}{\meter\per\second}
    \approx \SI{\round{\Var{A}/\Var{B}}{1}}{\meter\per\second}
  \end{equation*}

% initialize variables   
\initVariables
\item \textbf{An object is displaced \Var{A} meters in \Var{B} seconds.}
  \begin{equation*}
  v = \frac{\Delta s}{\Delta t}
    = \dfrac{\SI{\Var{A}}{m}}{\SI{\Var{B}}{s}}
    = \SI{\round{\Var{A}/\Var{B}}{5}}{\meter\per\second}
    \approx \SI{\round{\Var{A}/\Var{B}}{1}}{\meter\per\second}
  \end{equation*}
\end{enumerate}
\end{document}