Wsrtjtyk

How do i insert an underbraced under a transposed vector that spans over 2 elements in vector?

So for instance the first two elements under one underbracket with text "node 1", and ect..

the code for the vector:

documentclass{standalone}

usepackage{amsmath}



begin{equation}

    mathbf{D}_{right}^T =   left[ begin {array}{cccccccc} underbrace{0}_text{node 1}  &   underbrace{0}_text{node 1}   &  underbrace{0}_text{node 2}   &   underbrace{0}_text{node 2}   &      underbrace{ U_{x}}_text{node 3}  &   underbrace{ U_{y}}_text{node 3}   &   underbrace{cos left(theta right) Delta}_text{node 4}    &   underbrace{sin left(theta right) Delta}_text{node 4}   end {array}

 right]

end{equation}

You can do without an array here, since you're working with a single vector. Use ties (spaces, ~) to stretch out the elements:

documentclass{article}



usepackage{mathtools}



begin{document}



begin{equation}

  mathbf{D}_{mathrm{right}}^T = 

  bigl[~

    underbrace{mathstrut 0 ~~~ 0}_{mathclap{text{node 1}}} ~~ 

    underbrace{mathstrut 0 ~~~ 0}_{mathclap{text{node 2}}} ~~ 

    underbrace{mathstrut U_x ~~~ U_y}_{text{node 3}} ~~ 

    underbrace{cos(theta)Delta ~~~ sin(theta)Delta}_{text{node 4}}

  ~bigr]

end{equation}



end{document}

I'd recommend nested matrices; for the main one, use array with [t] vertical alignment.

documentclass{article}

usepackage{amsmath}



begin{document}



begin{equation}

mathbf{D}_{mathrm{right}}^T =

Bigl[

  begin{array}[t]{@{,}cccc@{,}}

  underbrace{mathstrutbegin{matrix} 0 & 0 end{matrix}}_{text{node 1}} &

  underbrace{mathstrutbegin{matrix} 0 & 0 end{matrix}}_{text{node 2}} &

  underbrace{mathstrutbegin{matrix} U_{x} & U_{y}end{matrix}}_{text{node 3}} &

  underbrace{mathstrut

    begin{matrix}cos(theta)Delta & sin(theta)Deltaend{matrix}

  }_{text{node 4}}

  end{array}

  Bigr]

end{equation}



end{document}

A TikZ solution, although I'm not too sure about its usefulness.

What might be advantageous of the Tikz way is the separation of vector elements and the brace markup in the source code. This might be useful when typesetting more complex / longer formulas in the cells.

However, this approach requires way more set-up than the other solutions.

documentclass{scrartcl}

usepackage{amsmath}

usepackage{tikz}

usetikzlibrary{matrix,decorations.pathreplacing,calc}

begin{document}

begin{equation}

    mathbf{D}_{right}^T =   

    begin{tikzpicture}  [baseline,

                          underbrace/.style={decorate,thick,decoration={brace,mirror}}]

                          matrix (eq1) [nodes={% Control for largest depth in vector

                                                % Change argument depth() to "deepest" node in vector

                                            text depth=depth("$U_y$")

                                        },

                                         anchor=base,

                                         matrix of math nodes,

                                         left delimiter=lbrack,

                                         right delimiter=rbrack,  

                                         column sep=5mm

                                        ] 

                          { 0 & 0 & 0 & 0 & U_x & U_y  & cos (theta) Delta & sin (theta) Delta  \}; 

                          % Specify braces in the format "column no where brace star/ closing column / description"

                          foreach x / y / nodedesc in {1/2/{node 1}, 3/4/{node 2}, 5/6/{node 3}, 7/8/{node 4}} 

                            draw [underbrace] (eq1-1-x.south west) -- (eq1-1-y.south east) node [below,midway] {nodedesc};                        

    end{tikzpicture}

end{equation}

end{document}