[Tex/LaTex] Define numeric variables

macrospackages

I would like to define some variables in a tex document. For example, I write in .tex something similar as: Our tool succeeds to validate x samples by Method A, and y samples by Method B. Thus its score is z. Where z is defined as x+y, and x (resp. y) is instanced somewhere else by a number, eg., 30 (resp. 50). As a result, after the compilation the text turns out to be Our tool succeeds to validate 30 samples by Method A, and 50 samples by Method B. Thus its score is 80.

The advantage of this, is that I just need to change the value of some variables, to change all the numbers in the text…

Does anyone know how to achieve this?

Best Answer

\documentclass{article}

\newcommand\x{30}
\newcommand\y{50}
\begin{document}

 I would like to define some variables in a tex document. For example,
 I write in .tex something similar as: Our tool succeeds to validate \x\
 samples by Method A, and \y\ samples by Method B. Thus its score is
 \the\numexpr\x+\y\relax. 

\end{document}

output-

Related Solutions

[Tex/LaTex] Completely expandable loop macro that also works in tabular

There are a number of possible approaches to doing this without the complexity: I'll cover a couple using expl3. First, if you don't mind keeping things non-expandable then you could do something like

\documentclass{article}
\usepackage{expl3}
\ExplSyntaxOn
\cs_new_protected:Npn \For #1#2#3#4
  {
    \int_step_inline:nnnn {#1} {#2} {#3 - 1} {#4}
  }
\cs_new_eq:NN \fpeval \fp_eval:n
\ExplSyntaxOff
\newcommand*\N{5}
\begin{document}

\begin{tabular}{|r|*{\N}{r|}}
    \hline
    $x$:   \For{0}{1}{\N}{&#1}\\
    \hline
    $e^x$: \For{0}{1}{\N}{& \fpeval{round(exp(#1),5)}}\\
    \hline
\end{tabular}
\end{document}

where the code to implement the cells can then be given at point-of-use. You could instead have a two-part setup where the functions are pre-coded: this is then expandable at point-of-use

\documentclass{article}
\usepackage{expl3}
\ExplSyntaxOn
\cs_new_protected:Npn \For #1#2#3#4
  {
    \int_step_function:nnnN {#1} {#2} {#3 - 1} #4
  }
\cs_new_eq:NN \fpeval \fp_eval:n
\ExplSyntaxOff
\newcommand*\N{5}
\newcommand\CellNumber[1]{&#1}
\newcommand\CellExp[1]{&\fpeval{round(exp(#1),5)}}
\begin{document}
\begin{tabular}{|r|*{\N}{r|}}
    \hline
    $x$:   \For{0}{1}{\N}\CellNumber\\
    \hline
    $e^x$: \For{0}{1}{\N}\CellExp\\
    \hline
\end{tabular}
\end{document}

In both cases, the \int_step_... functions work much like David's answer: the loop itself is done by expansion. You can't do an assignment to \x or similar and have expandability.

An alternative approach if you are using LuaTeX is to do everything in Lua: the primitive here is expandable so you can use a perhaps more familiar approach (the question suggests a C background).

\documentclass{article}
\newcommand\For[4]{%
  \directlua{%
    for x = #1, (#3 - 1), #2 do
      tex.print(#4)
    end
  }%
}
\newcommand*\N{5}
\makeatletter
\let\Percent\@percentchar
\makeatother
\begin{document}

\begin{tabular}{|r|*{\N}{r|}}
    \hline
    $x$:   \For{0}{1}{\N}{"&" .. x}\\
    \hline
    $e^x$: \For{0}{1}{\N}{"&" .. string.format("\Percent.3f", math.exp(x))}\\
    \hline
\end{tabular}
\end{document}

For the number formatting, we need % which is a bit awkward in TeX: I've given a 'user' name to the LaTeX kernel command \@percentchar (a % which isn't a comment char).

[Tex/LaTex] How to define variables with white space

Your approach is wrong under many respects.

You should use math italic, not \emph, except for multiletter variables; on the other hand “Training” is text, so it should be upright.
Math formulas should be in math mode, even if it's just one variable.

\newcommand{\varu}{u}
\newcommand{\varv}{v}
\newcommand{\varz}{z}
\newcommand{\varTr}{\mathrm{Training}}
\newcommand{\varRzT}{R_{\varz_{\varTr}}}
\newcommand{\varReaz}{R_{EAz}}
\newcommand{\varRecScore}{s(\varv,\vart\mid\varu)}
\newcommand{\varCS}{\mathrm{Cand\ Set}}
\newcommand{\varw}{w(\varu,\varv)}
\newcommand{\varBC}{\mathrm{BC}_{\mathrm{suff}}}

Then your text might be, more simply,

My text is quite long. In the text there can 
be referred some variables like $\varu$
and after the variable there is a white space.
\begin{equation}
(\varu,\varv) = \varu * \varv - \varRzT
\end{equation}

Best Answer

Related Solutions

[Tex/LaTex] Completely expandable loop macro that also works in tabular

[Tex/LaTex] How to define variables with white space

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