Crthuky

A noticeable downside to aesthetics in the vec notation is that, for "short" and "tall" characters (a, i, v vs b, k, l), the overset vector notation shows difference in its height from the baseline. Is it possible to define (or redefine) overset characters to show a fixed, consistent height from the baseline (or any other horizontal standard), regardless of the character it is set upon? Below is a quick, crude comparison of the status quo and the objective:

Status Quo: Heights vary.

Objective: Heights are consistent.

ANOTHER EDIT: The customised vector comes from a script written by the user Todd Lehman:

makeatletter
newlengthxvec@height%
newlengthxvec@depth%
newlengthxvec@width%
newcommandxvec[2][]%
 ifmmode%
 settoheightxvec@height$#2$%
 settodepthxvec@depth$#2$%
 settowidthxvec@width$#2$%
 else%
 settoheightxvec@height#2%
 settodepthxvec@depth#2%
 settowidthxvec@width#2%
 fi%
 defxvec@arg#1%
 defxvec@dd:%
 defxvec@d.%
 raisebox.2exraiseboxxvec@heightrlap%
 kern.05em% (Because left edge of drawing is at .05em)
 begintikzpicture[scale=1]
 pgfsetroundcap
 draw (.05em,0)--(xvec@width-.05em,0);
 draw (xvec@width-.05em,0)--(xvec@width-.15em, .075em);
 draw (xvec@width-.05em,0)--(xvec@width-.15em,-.075em);
 ifxxvec@argxvec@d%
 fill(xvec@width*.45,.5ex) circle (.5pt);%
 elseifxxvec@argxvec@dd%
 fill(xvec@width*.30,.5ex) circle (.5pt);%
 fill(xvec@width*.65,.5ex) circle (.5pt);%
 fifi%
 endtikzpicture%
 %
 #2%

makeatother

letstdvecvec
renewcommandvec[1]xvec[]#1

% --- Define dvec and ddvec for dotted and double-dotted vectors.
newcommanddvec[1]xvec[.]#1
newcommandddvec[1]xvec[:]#1

Here's a quick low-tech solution:

documentclassarticle

newcommandmyvec[1]vecvphantomA#1

begindocument

$myvecacdotmyvecb$

enddocument

This will adjust automatically for for sub/superscripts but has an issue (see below) if the vector symbol is above a character taller than A.

A slightly more complicated version using ooalign will force the vector to be at a height as if it is above A even if it's placed over something taller.

The top line is the simple version above, where the third vector is out of allignment since A^2 is taller than A. The second line uses the code

newcommandmyvec[1]ooalignhfil$vecvphantomA$hfilcrhfil$#1$hfilcr

but will not adjust to subscript size changes. If you want, you can fix that using mathchoice:

newcommandmyvec[1]mathchoice
ooalignhfil$vecvphantomA$hfilcrhfil$#1$hfilcr
ooalignhfil$vecvphantomA$hfilcrhfil$#1$hfilcr
ooalignhfil$vecvphantomscriptstyle A$hfilcrhfil$scriptstyle #1$hfilcr
ooalignhfil$vecvphantomscriptscriptstyle A$hfilcrhfil$scriptscriptstyle #1$hfilcr

Note that I would avoid renewing the vec command since the high arrows look odd to me when above short letters. Compare myvecacdotmyveca with vecacdotveca.

Update:

As a final option (my favorite), one could define myvec with 2 parameters: one optional. The required parameter is the printed letter with the arrow, the second, optional parameter is a character that sets the height of the arrow.

So myvec[t]a would give you a vector over the a at the height of the t. Omitting the optional argument gives you the same result as vec. The line above is produced from the code:

$myvecacdotvecaquadmyvec[t]acdotvectquadmyvec[j]acdotvecjquadmyvec[b]acdotvecbquadmyvec[A]acdotvecA$

The code for myvec is

newcommandmyvec[2][]vecvphantom#1#2

and it will adjust for sub/superscripts as in $A_myvec[t]acdotvect$.