Mdthbs

I would like the formulae in the third column to be vertically aligned to the middle, i.e. the formulae should be vertically at the middle of the two lines of the descriptions.

documentclass{article}

usepackage{amsmath}

usepackage{tabularx,booktabs}

usepackage{caption}

begin{document}

begin{table}[htb]

    centering

    caption{I would like the formulae here to be vertically at the middle of the two lines of text}

    begin{tabularx}{linewidth}{lX>{$}c<{$}}

        toprule

        Name & Description & multicolumn{1}{c}{Formula}\

        midrule

        Ducks & Something which goes on two lines, something which goes on two lines &

        A=dfrac{B}{C}\

        Lions & Something which goes on two lines, something which goes on two lines &

        D=dfrac{E}{F}\

        bottomrule

    end{tabularx}

end{table}

begin{table}[htb]

    centering

    caption{Here the formulae are correctly aligned with the description, but I would like the name at the top like in the previous table}

    begin{tabular}{lm{24em}>{$}c<{$}}

        toprule

        Name & Description & multicolumn{1}{c}{Formula}\

        midrule

        Ducks & Something which goes on two lines, something which goes on two lines &

        A=dfrac{B}{C}\

        Lions & Something which goes on two lines, something which goes on two lines &

        D=dfrac{E}{F}\

        bottomrule

    end{tabular}

end{table}

end{document}

Like this:

Edit:

Position of column contents determined by in row baseline, which is (unfortunately) cannot be changed from column to column.

So far I don't see any other possibility as use boxes in the last or the first column, which enables align their baseline. Good candidate for your particular case is adjustbox:

documentclass{article}

usepackage{amsmath}

usepackage{tabularx,booktabs}

usepackage{caption}



usepackage{adjustbox}



begin{document}

begin{table}[htb]

    centering

    caption{I would like the formulae here to be vertically at the middle of the two lines of text}

    begin{tabularx}{linewidth}{lXc}

        toprule

        Name & Description & Formula    \

        midrule

        Ducks & Something which goes on two lines, something which goes on two lines &

        adjustbox{valign=t}{$A=dfrac{B}{C}$}\

        Lions & Something which goes on two lines, something which goes on two lines &

        adjustbox{valign=t}{$D=dfrac{E}{F}$}\

        bottomrule

    end{tabularx}

end{table}

end{document}

For more convenient writing of table you can define new column type:

newcolumntype{E}{>{begin{adjustbox}{valign=t}$}c<{$end{adjustbox}}}

and than wrote table (body) as:

    begin{tabularx}{linewidth}{lXE}

        toprule

        Name & Description & Formula    \

        midrule

        Ducks & Something which goes on two lines, something which goes on two lines &

        A=dfrac{B}{C}\

        Lions & Something which goes on two lines, something which goes on two lines &

        D=dfrac{E}{F}\

        bottomrule

    end{tabularx}

If the text in cells of the middle column has arbitrary lines or if the equation is simple with only one line, then result is worse. In such a cases possible solution is use of multirow cells in the first column and manually adjust number of columns which those cells spans and in the second column set baseline in vertical middle:

documentclass{article}

usepackage{amsmath}

usepackage{booktabs, multirow, tabularx}

usepackage{caption}



usepackage{adjustbox}

usepackage{lipsum}



begin{document}

begin{table}[htb]

    centering

    renewcommandtabularxcolumn[1]{m{#1}} % <---

    caption{I would like the formulae here to be vertically at the middle of the two lines of text}

    begin{tabularx}{linewidth}{lX>{$}c<{$}}

        toprule

        Name & Description & Formula    \

        midrule

multirow{-6}{*}{Ducks} % <--- manually adjusted

      & lipsum[66] & A=dfrac{B}{C}\

        bottomrule

    end{tabularx}

end{table}

end{document}

or use solution proposed in @Bernard's answer.

This is rather hard: the problem is that you want to align the middle box in two ways: on the left along the baseline, on the right along the center. This type of table normally requires either nesting of tables (which is difficult with tabularx) or measuring some of the content to use llap tricks.

We are missing here tabular code based on xcoffins which has more than one handle ...

documentclass{article}

usepackage{amsmath}

usepackage{tabularx,booktabs}

usepackage{caption,xcoffins}

newlengthcolA



begin{document}

begin{table}[htb]

    centering

    renewcommand{tabularxcolumn}[1]{m{#1}}

    settowidthcolA{begin{tabular}{l}Name\Ducks\Lionsend{tabular}}

    caption{I would like the formulae here to be vertically at the middle of the two lines of text}

    begin{tabularx}{linewidth}{p{dimexprcolA-2tabcolsep}X>{$}c<{$}}

        toprule

        Name & Description & multicolumn{1}{c}{Formula}\

        midrule

             &leavevmodellap{makebox[colA][l]{Ducks}}Something which goes on two lines, something which goes on two lines &

        A=dfrac{B}{C}\

             &leavevmodellap{makebox[colA][l]{Lions}}Something which goes on two lines, something which goes on two lines and on one more line and on one more line and on one more line &

        D=dfrac{E}{F}\

        bottomrule

    end{tabularx}

end{table}



%Only for show some coffin code:



NewCoffinCoffinA

NewCoffinCoffinB

NewCoffinCoffinC



SetHorizontalCoffinCoffinA{Ducks}

SetHorizontalCoffinCoffinC{$D=dfrac{E}{F}$}



SetVerticalCoffinCoffinB{dimexpr textwidth-CoffinWidthCoffinA-CoffinWidthCoffinC-6tabcolsep}{noindent Something which goes on two lines, something which goes on two lines and on one more line and on one more line and on one more line}



JoinCoffinsCoffinA[H,r]CoffinB[T,l](2tabcolsep,0pt)

JoinCoffinsCoffinA[vc,r]CoffinC[vc,l](2tabcolsep,0pt)

noindenthspace*{tabcolsep}TypesetCoffinCoffinA

end{document}

Here a solution based on the redefinition of the X column type, and two possible hacks for the first column (they may have to be adapted to the real contents):

documentclass{article}

usepackage{amsmath}

usepackage{tabularx, booktabs, makecell}

renewcommand{tabularxcolumn}[1]{m{#1}}



begin{document}



begin{table}[htb]

    centering

    begin{tabularx}{linewidth}{lX>{$}c<{$}}

        toprule

        Name & Description & multicolumn{1}{c}{Formula}\

        midrule

       makecell[l]{Ducks\mbox{}} & Something which goes on two lines, something which goes on two lines &

        A=dfrac{B}{C}\

addlinespace

        makecell[l]{Lions\mbox{}} & Something which goes on two lines, something which goes on two lines &

        D=dfrac{E}{F}\

addlinespace

       raisebox{1.4ex}{Lions} & Something which goes on two lines, something which goes on two lines &

        D=dfrac{E}{F}\

        bottomrule

    end{tabularx}

end{table}



end{document}