On Wed, Aug 6, 2008 at 12:21 PM, Bruno Voisin <[EMAIL PROTECTED]> wrote: > Le 6 août 08 à 09:34, Oliver Buerschaper a écrit : > >> does someone know how to find out the current value of >> default_rule_thickness in a (La)TeX document? TeX uses it to determine the >> line width of fraction bars and roots in math mode … > > The short story: 0.4 pt. > > The long story: LaTeX defines \frac in terms of the TeX primitive \over, and > \sqrt in terms of the TeX primitive \radical (a primitive being a command > defined in the source code of TeX itself). Hence the only way to get an > answer for sure would be to inspect the source code of TeX. > > The TeXbook has an appendix G "Generating boxes from formulas" mentioning in > several places (for \overline, \underline, \radical, ...) a > default_rule_thickness called either $\theta$ or $\xi_8$, but not giving its > value. Being a mere mortal, I must admit I can't make much sense of this > appendix. > > My feeling is that TeX uses the same default rule thickness for all rules > (in \overline, \underline, \over, \sqrt, \footnote, ...) and that it is the > thickness given at the beginning of chapter 21 "Making Boxes": > > \hrule width=<depends on contest>, height=0.4pt, depth=0.0pt > \vrule width=0.4pt, height=<depends on contest>, depth=<depends on contest>
The rule is between 0.4pt and 0.5pt \starttext \dontleavehmode \scale[factor=200]{$1 \over 2$} \scale[factor=200]{$1 \above .47pt 2$} \stoptext > Now, if you want to specify the rule thickness yourself for a fraction, say > to 1pt, I see two solutions: > > - In plain TeX, replace \over by \above. For example, replace {a\over b} by > {a\above1pt b}. > > - In LaTeX, use the amsmath package and replace \frac by \genfrac. For > example, replace \frac{a}{b} by \genfrac{}{}{1pt}{}{a}{b}. > > I don't know what can be done for square roots. > > Bruno Voisin > > PS Normally, such a question which has nothing Mac-specific would be better > posted to a general LaTeX forum such as comp.tex.text. However, > comp.tex.text may be quite intimidating to the novice (chances are you'll > either get your question ignored or be flamed for asking a stupid question), > and as a result I have myself asked general questions here more than once > and avoid comp.tex.text whenever possible. Wolfgang ___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki! maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://tex.aanhet.net archive : https://foundry.supelec.fr/projects/contextrev/ wiki : http://contextgarden.net ___________________________________________________________________________________