Unable to add multiline in the text box in flowchart

Question

% flowchart drawing
\documentclass[a4paper, 12pt]{report}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{float}



\usepackage{tikz}
\usetikzlibrary{shapes.geometric, arrows}
\tikzstyle{rect} = [rectangle, rounded corners, minimum width=3cm, minimum height=1cm,text centered, draw=black, fill=white]
\tikzstyle{arrow} = [thick,->,>=stealth]
\usetikzlibrary{shapes.multipart}

\begin{document}
\begin{figure}[H]
    \centering
    \begin{tikzpicture}[node distance=2cm]
        \node (one) [rect] {Input excitation $p_{i+1}$ };
        \node (two) [rect, below of=one] {Calculate displacement response: $x_{i+1} = x_{i} + \Delta t \mathit{x1}_{i} +  \frac{\Delta t^2}{2} \mathit{x2}_{i}$ };
        \node(three)[rect, below of=two]{Impose $x_{i+1}$ on test structure};
        \node(four)[rect, below of=three]{Measure restoring forces from $\mathit{fs}_{i+1}$ from the test  structure}; 
        \node(five)[rect, below of=four]{Calculate: $\mathit{x2}_{i+1} = \left[m + \frac{\mathit{\Delta t}}{2} c\right]^{-1} \left[p_{i+1} - \mathit{fs}_{i+1} - c \mathit{x1}_{i} - \frac{\mathit{\Delta t}}{2} c \mathit{x2}_{i}\right]  \mathit{x1}_{i+1} = \mathit{x1}_{i} + \frac{\mathit{\Delta t}}{2}\left(\mathit{x2}_{i} + \mathit{x2}_{i+1}\right) $};
        \node(six)[rect, below of=five]{set $i = i+1$};
        \draw [arrow] (one) -- (two);
        \draw [arrow] (two) -- (three);
        \draw [arrow] (three) -- (four);
        \draw [arrow] (four) -- (five);
        \draw [arrow] (five) -- (six);
        \draw [arrow] (six.east) -- ++(5, 0) --  ++ (0, 10) -- (one) ;
    \end{tikzpicture}
    \caption{Newmark Explicit Scheme flowchart}
    \label{flowchart}
\end{figure}


\end{document}

What is your question? Please add a short but clear description of your problem. In this case it is probably also helpful to add a picture of the rendered output of your code. — schtandard, Jun 07 '19 at 11:34
Also, don't use [H]. That's like giving someone a car so they can get where they need to be but taking of all the wheels first. In LaTeX terms, don't use a floating environment (like figure), if you don't want it to float around. — schtandard, Jun 07 '19 at 11:37
Does this help https://tex.stackexchange.com/questions/123671/manual-automatic-line-breaks-and-text-alignment-in-tikz-nodes — jak123, Jun 07 '19 at 12:01

Zarko · Accepted Answer · 2019-06-07T18:00:08.660

Like this?

For above flowchart I made the following changes in your MWE (Minimal Working Example):

Define text width for node style rect. For its size I select 66 mm. It forse nodes contents, which is wider than text width, is breaken into more lines (with this is solved your main problem)
Since \tikzstyle is obsolete syntax, instead it I use\tikzset`
For placement I use TikZ library positioning and chains
For arrows between nodes is used macro join=by ...

% flowchart drawing
\documentclass[a4paper, 12pt]{report}
\usepackage{caption}

\usepackage{tikz}
\usetikzlibrary{arrows.meta,
                chains, 
                positioning,
                shapes.geometric,
                shapes.multipart 
                }
\tikzset{rect/.style = {rectangle, draw, rounded corners, 
\tikzset{rect/.style = {rectangle, draw, rounded corners, 
                        minimum width=#1, minimum height=9mm,
                        text width =\pgfkeysvalueof{/pgf/minimum width}-
                                    2*\pgfkeysvalueof{/pgf/inner xsep},
                        align=center,
                        on chain=A, join=by arrow},
       rect/.default = 66mm,
        arrow/.style = {thick,-Stealth}
        }

\begin{document}
\begin{figure}[htb]
    \centering
    \begin{tikzpicture}[
    node distance=7mm and 1mm,
      start chain= A going below
                        ]
\node [rect] {Input excitation $p_{i+1}$ };
\node [rect] {Calculate displacement response:\\[1ex] 
              $x_{i+1} = x_{i} + \Delta t \mathit{x1}_{i} + \frac{\Delta t^2}{2} \mathit{x2}_{i}$ };
\node [rect] {Impose $x_{i+1}$ on test structure};
\node [rect] {Measure restoring forces from $\mathit{fs}_{i+1}$ 
              from the test  structure};
\node [rect] {Calculate:\\ 
              $
              \mathit{x2}_{i+1} =
              \Bigl[m + \frac{\mathit{\Delta t}}{2} c\Bigr]^{-1}
              \Bigl[p_{i+1} - \mathit{fs}_{i+1} - c \mathit{x1}_{i} - %\\
               \frac{\mathit{\Delta t}}{2} c \mathit{x2}_{i}\Bigr]  \mathit{x1}_{i+1}%\\
              = \mathit{x1}_{i} + \frac{\mathit{\Delta t}}{2}\Bigl(\mathit{x2}_{i} + \mathit{x2}_{i+1}\Bigr)
              $
              };
\node [rect] {set $i = i+1$};
        \draw [arrow] (A-6.east) -- ++(1, 0) |- (A-1) ;
    \end{tikzpicture}
    \caption{Newmark Explicit Scheme flowchart}
    \label{flowchart}
\end{figure}
\end{document}

Unable to add multiline in the text box in flowchart

1 Answers1