Define numeric variables

Question

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?

Your example doesn't need any arithmetic, just \newcommand\x{80} ... \x score is \x\% if you need arithmetic does it just need integers or floating point values (quite different answers in those cases) — David Carlisle, May 05 '14 at 14:15
You didn't answer the question about whether you need floating point values. \the\numexpr 5 / 6\relax divides 5 by 6 returning an integer but TeX doesn't have floating point values so if you need non integer values you'd need to use lengths \the\dimexpr 5pt /6 \relax and then remove the pt (or use a package that does that) — David Carlisle, May 05 '14 at 14:31

score 44 · Accepted Answer · edited Oct 15 '17 at 14:08

44

\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-

edited Oct 15 '17 at 14:08

Stefan Pinnow

29,535

answered May 05 '14 at 14:44

David Carlisle

757,742

1

Thank you... I see how you define x and y, and what if I still want to define a newcommand z which is x+y? How to write this definition? – SoftTimur May 05 '14 at 23:00
1

@SoftTimur \newcommand\myadd[2]{\the\numexpr(#1)+(#2)\relax}} ... \myadd\x\y – David Carlisle May 05 '14 at 23:05
That works... just another question: how much space does the second \ of \x\ add after a number? is it exactly equivalent to a normal space after a number? – SoftTimur May 05 '14 at 23:53
1

@SoftTimur yes. – David Carlisle May 06 '14 at 00:04
@DavidCarlisle why does this not support in pgf-umlcd? I try - \begin[text width = \x\ cm]{interface}{\x\, \y\}. – alhelal Oct 15 '17 at 13:44
@DavidCarlisle this works when I use \x{} instead of \x or \x\ – alhelal Oct 15 '17 at 13:49
\x{} not work for value greater than 9 or less than -9.\x supports for all yet. – alhelal Oct 15 '17 at 18:27
@DavidCarlisle I try \fontsize{17}{\the\numexpr\x*1.2\relax} but not work. ! Illegal unit of measure (pt inserted). – alhelal May 06 '19 at 02:03
@alhelal numexr are __integer_ expressions like latex counters you can not multiply by 1.2 (or even store the value of the result ) – David Carlisle May 06 '19 at 08:54
How to perform a modulo using this syntax? – Someone Aug 21 '20 at 12:47
Does it work for negative numbers? Eg.if $x= 30$, $y = -50$, then $z$ will print $-20$? – somenxavier May 31 '21 at 15:51
1

@somenxavier you could have tried it in less tine than it took to ask:-) yes why wouldn't it work? – David Carlisle May 31 '21 at 15:53

egreg · Answer 2 · 2020-06-09T13:45:45.537

You can use expl3 features, in particular the xfp package, which features \fpeval and \inteval.

\documentclass{article}
\usepackage{xfp}

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

\begin{document}

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

\end{document}

Of course you could also use \x{} instead of \inteval{\x}, but with the \inteval method you can also do

\newcommand{\z}{\x+3*\y}

and use \inteval{\z}.

This assumes operations on integer; if you need floating point, you can use \fpeval instead of \inteval (but things get more complex).

With a current LaTeX release (after 2020-10-01), there's no need to load xfp. — egreg, Feb 21 '23 at 17:26

Zombo · Answer 3 · 2020-08-21T14:22:08.133

10

You can use counters for this:

\newcounter{x}
\setcounter{x}{30}
\newcounter{y}
\setcounter{y}{50}
Our tool succeeds to validate \arabic{x} samples by Method A,
and \arabic{y} samples by Method B. Thus its score is 
\the\numexpr\value{x}+\value{y}.

edited Aug 21 '20 at 14:22

answered Mar 20 '16 at 04:38

Zombo

1

1

nice solution but doesn't allow for floating point vars. – Jubei Feb 15 '21 at 23:22

Define numeric variables

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