LaTeX forum ⇒ Math & ScienceRecommend an \ifnum introduction

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Recommend an \ifnum introduction

Postby LaTexLearner » Sun Sep 18, 2016 9:13 pm

Can anybody recommend an introduction to the \ifnum commands?

I can't make sense of code that has them but I'd like to learn how they work.



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Postby cgnieder » Sun Sep 18, 2016 9:51 pm

\ifnum is a TeX primitive conditional for comparing integers:

  1. \ifnum1=1
  2. true
  3. \else
  4. false
  5. \fi % yields true
  7. \ifnum1<2
  8. true
  9. \else
  10. false
  11. \fi % yields true
  13. \ifnum1>2
  14. true
  15. \else
  16. false
  17. \fi % yields false
  19. \bye

\ifnum and all other primitives are explained in the TeX book or in TeX by topic: texbytopic.

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Stefan Kottwitz
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Postby Stefan Kottwitz » Mon Sep 19, 2016 10:23 am

Perhaps you may also be interested in the ifthen package.

Also, some modern packages such as pgf provide tools for comparing or calculating. More complex calculations could be done using LuaTeX. I use LuaTeX and binary math for calculating subnet IP addresses, for example.

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