7.6.1 Top new questions this week

7.6.1.1 Expand an argument into a string
7.6.1.2 Table formatting: remove horizontal and vertical borders from only specific cells
7.6.1.3 Underbrace under square root sign plain TeX
7.6.1.4 Side brace only some equations
7.6.1.5 tikz: Log-Log Graph Missing Grid Lines
7.6.1.6 Is it okay to use \center and \justify without \endcenter and \endjustify?
7.6.1.7 Trying to understand the interaction between baskervillef and fontspec
7.6.1.1 Expand an argument into a string

https://tex.stackexchange.com/landing/r/digest?cta=question&id=580190

I would like to build a TeX macro that would transform its argument by expanding every number into a sequence of letter (always the same letter). For example 3(2)2(1) should produce AAA(AA)AA(A). 
I ... 
[macros] [tex-core]
 
asked by perror https://tex.stackexchange.com/landing/r/digest?cta=user&id=23294 7 votes
answered by David Carlisle https://tex.stackexchange.com/landing/r/digest?cta=user&id=1090 6 votes
7.6.1.2 Table formatting: remove horizontal and vertical borders from only specific cells

https://tex.stackexchange.com/landing/r/digest?cta=question&id=580245

The MWE below creates a 3 x 3 table. The included text above the table describes the specific cells where I want no borders. 
I believe the solutions lies with the correctly using \cline command ... 
[tables] [formatting]
 
asked by WyoWindStorm https://tex.stackexchange.com/landing/r/digest?cta=user&id=184615 6 votes
answered by Zarko https://tex.stackexchange.com/landing/r/digest?cta=user&id=18189 6 votes
7.6.1.3 Underbrace under square root sign plain TeX

https://tex.stackexchange.com/landing/r/digest?cta=question&id=580082

$$ 
\rlap{$\sqrt{\phantom{\displaystyle\pmatrix{A^{-1} b(x)\cr -1}^T 
\pmatrix{A & b(x) \cr b(x)^T & \Phi(x,x)} 
\pmatrix{A^{-1} b(x) \cr -1}}}$} 
\mskip14mu 
\... 
[math-mode] [plain-tex] [underbrace] [sqrt]
                                                                                  

                                                                                  
 
asked by User https://tex.stackexchange.com/landing/r/digest?cta=user&id=43121 6 votes
answered by Mico https://tex.stackexchange.com/landing/r/digest?cta=user&id=5001 6 votes
7.6.1.4 Side brace only some equations

https://tex.stackexchange.com/landing/r/digest?cta=question&id=579883

Im trying but failing since quite some time now to get the following: 
I've got 6 equations aligned and I want to brace the first 4 of them with some text behind. 
But my result is this something like ... 
[equations] [align] [arrays] [braces]
 
asked by user596542 https://tex.stackexchange.com/landing/r/digest?cta=user&id=233504 6 votes
answered by campa https://tex.stackexchange.com/landing/r/digest?cta=user&id=82917 4 votes
7.6.1.5 tikz: Log-Log Graph Missing Grid Lines

https://tex.stackexchange.com/landing/r/digest?cta=question&id=579951

I am attempting to plot a log-log graph with bounds not falling on a factor of 10.  In my case, the y-axis goes from ymin=0.3 to ymax=300.  As you can see in the screenshot, the minor grid lines for y=... 
[tikz-pgf]
 
asked by grfrazee https://tex.stackexchange.com/landing/r/digest?cta=user&id=81543 6 votes
7.6.1.6 Is it okay to use \center and \justify without \endcenter and \endjustify?

https://tex.stackexchange.com/landing/r/digest?cta=question&id=579856

I would argue no.  I know that \endcenter and \endjustify are not trivial (both call \endtrivlist).  While they do not generate error messages, that does not mean they don't produce errors, just that ... 
[environments]
 
asked by John Kormylo https://tex.stackexchange.com/landing/r/digest?cta=user&id=34505 6 votes
answered by David Carlisle https://tex.stackexchange.com/landing/r/digest?cta=user&id=1090 7 votes
7.6.1.7 Trying to understand the interaction between baskervillef and fontspec

https://tex.stackexchange.com/landing/r/digest?cta=question&id=580328

My high level goal is to get a good, free Baskerville font working that supports smallcaps and "rare" ligatures. I have achieved this, apart from rare ligatures, using the baskervillef ... 
[fonts] [fontspec] [ligatures]
 
asked by Vermoulian https://tex.stackexchange.com/landing/r/digest?cta=user&id=233720 5 votes