I have MiKTeX 2.3 and its version of e-TeX does not support
\dimexpr command. I do not want to update this MiKTeX now and wonder, is it possible to define the
\dimexpr command, probably with use of
No, it is not possible to define it yourself but probably you do not need to anyway. Th
\dimexpr primitive is provided by e-TeX, and since it is a primitive ('build in') it cannot be properly simulated by a macro. However, e-TeX has been around for many years. Older TeX systems used to require you to explicitly ask for e-TeX, so using
pdfelatex, etc. Thus you should try inserting an '
e' into whichever command you currently use to run TeX: I would guess you use either
pdflatex, so try
pdfelatex as a replacement.