How about supporting functions like ABS as EXP in a better way than just as a function name.

CodeCogs, I will try to post a better - perhaps a tiny bit formal - suggestion about how sheet references could be translated to matrix references, in a later post.

For now I would like to point out that not translating the cell references can lead to ambiguous math expressions. Take e.g. your (1) rendering: The sigma suggests a sum is to be taken, but of what? Some inner product of B5 and D56 ? (see the meaning a colon can take: http://en.wikipedia.org/wiki/Table_of_mathematical_symbols) And should B4 be interpreted as B times 4 and D56 as D times 56. Or should the cell values of these references be substituted? As the maker of the rendering you are aware you mean to indicate a spreadsheet cell range, but does any reader share the same insight.

One is of course totally free to think of the add-in as a means to personally doodle a bit with a mix of spreadsheet references and math symbols but in the end - for more serious stuff - one still needs to clarify what the renderings mean just to avoid ambiguity.

I'm not saying all this to pester you or Deedee - in fact I found Deedee's feedback much inspiring to try to formulate my suggestions better - but my main concern is with the usability of the add-in renderer. As I see it it could act as a kind of macro language for the input of LaTeX expressions, so spreadsheet formulas can be used to render valid math expressions. If you agree on this - even if not all and everything I propose can be implemented - that would be great. If however you see the add-in renderer as a toy that is intended to render math like expressions that are a hybrid between formulas and math expressions I would feel sad as I see this as a missed opportunity to create something very useful.

[If any math teachers read this I would value their feedback on this very much. Do you share the 'purist' view, or are you content with the 'hybrid' renderings?]

Addins? I don't use add-ins. I'm a Google Docs spreadsheet user and I found CodeCogs one day because the LaTeX math expression maker in the old Google Docs text editor proved to be too limited. I love the CodeCogs on-line editor since, although I hoped it would be easier to invoke the editor from the image URL (now both URLs are a bit too dissimilar)