TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I used the following construct quite often:


But when I try to adjust the size a small bit, like this:


I get

! Package calc Error: `.' invalid at this point.

What am I doing wrong?

share|improve this question
up vote 19 down vote accepted

The calc package allows only division by integers or by reals which are announced as \real: so


will do, but


works as well, doesn't require calc and is faster.

share|improve this answer
Thanks! I really should read a bit about TeX syntax - because this was not very obvious. – Rogach Apr 23 '12 at 7:44

You can use

share|improve this answer

Great "short" answers!

Just to expand into the general concept that will answer this question in a more understandable way:

Wherever you have a macro that expands into a length for instance: \parskip, \linewidth, ... Or in this case \textwidth you can create another length just by setting a floating point factor before the macro.

For example:

  • 0.78\parskip
  • 2\linewidth
  • ...

or in your case 0.45\textwidth

are valid values for the parameter width in includegraphics

You can take a look at the first lines of the wiki article: http://en.wikibooks.org/wiki/LaTeX/Lengths

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.