Bdtjtk

I want to make a table with two columns:

• on the left side, I want to put 2 aligned equations


• on the right side, I want to put a graph.

In the following MCVE, the 2 equations are on the left side but with a huge unused space between them. I want to place those 2 equation just next to the graph

documentclass[a4paper, 12pt]{book}

usepackage{pgfplots, tikz}

begin{document}

begin{tabular}{cc}

    $

    frac{u_{i+1,j} - u_{i,j}}{Delta t} = kappa frac{u_{i,j-1} - 2u_{i,j} + u_{i,j+1}}{(Delta x)^2}$ \

    $u_{i+1,j} = u_{i,j} + frac{kappa Delta t}{(Delta x)^2}(u_{i,j-1} - 2u_{i,j} + u_{i,j+1})

    $

    &

    begin{tikzpicture}

    [scale = 0.7]

    %[scale = 0.7, every node/.style={scale = 0.7}]

    % Draw axes

    draw [<->,thick] (0,5) node (yaxis) [above] {$y$}

    |- (5,0) node (xaxis) [right] {$x$};



    coordinate (c) at (2,2);

    fill[red] (c) circle (3pt);

    draw[dashed] (yaxis |- c) node[left] {$scriptstyle{i}$}

    -| (xaxis -| c) node[below] {$scriptstyle{j-1}$};



    coordinate (d) at (3,2);

    fill[red] (d) circle (3pt);

    draw[dashed] (yaxis |- d) node[left] {$scriptstyle{i}$}

    -| (xaxis -| d) node[below] {$scriptstyle{j}$};



    coordinate (d) at (3,3);

    fill[red] (d) circle (3pt);

    draw[dashed] (yaxis |- d) node[left] {$scriptstyle{i+1}$}

    -| (xaxis -| d) node[below] {$scriptstyle{j}$};



    coordinate (d) at (4,2);

    fill[red] (d) circle (3pt);

    draw[dashed] (yaxis |- d) node[left] {$scriptstyle{i}$}

    -| (xaxis -| d) node[below] {$scriptstyle{j+1}$};



    draw [thin, gray] (0,0) grid (5,5);

    end{tikzpicture}\

end{tabular}

end{document}

I propose this somution with the equations inserted in a gathered environment,, and a raisebox for the graph:

documentclass[a4paper, 12pt]{book}

usepackage{pgfplots, tikz}

usepackage{mathtools }



begin{document}



begin{tabular}{cc}

  leavevmode $ begin{gathered}

    frac{u_{i+1,j} - u_{i,j}}{Delta t} = kappa frac{u_{i,j-1} - 2u_{i,j} + u_{i,j+1}}{(Delta x)^2} \

    u_{i+1,j} = u_{i,j} + frac{kappa Delta t}{(Delta x)^2}(u_{i,j-1} - 2u_{i,j} + u_{i,j+1})

  end{gathered} $

    &

    raisebox{-0.5height}{begin{tikzpicture}

    [scale = 0.7]

    %[scale = 0.7, every node/.style={scale = 0.7}]

    % Draw axes

    draw [<->,thick] (0,5) node (yaxis) [above] {$y$}

    |- (5,0) node (xaxis) [right] {$x$};



    coordinate (c) at (2,2);

    fill[red] (c) circle (3pt);

    draw[dashed] (yaxis |- c) node[left] {$scriptstyle{i}$}

    -| (xaxis -| c) node[below] {$scriptstyle{j-1}$};



    coordinate (d) at (3,2);

    fill[red] (d) circle (3pt);

    draw[dashed] (yaxis |- d) node[left] {$scriptstyle{i}$}

    -| (xaxis -| d) node[below] {$scriptstyle{j}$};



    coordinate (d) at (3,3);

    fill[red] (d) circle (3pt);

    draw[dashed] (yaxis |- d) node[left] {$scriptstyle{i+1}$}

    -| (xaxis -| d) node[below] {$scriptstyle{j}$};



    coordinate (d) at (4,2);

    fill[red] (d) circle (3pt);

    draw[dashed] (yaxis |- d) node[left] {$scriptstyle{i}$}

    -| (xaxis -| d) node[below] {$scriptstyle{j+1}$};



    draw [thin, gray] (0,0) grid (5,5);

    end{tikzpicture}}\

end{tabular}



end{document}