Non-Floating Centering: When The Center Environment Shines In Latex

Aligning Content Without Floats

LaTeX provides extensive capabilities for precisely positioning and aligning content on the page using floating environments like figure and table. However, in some cases floating environments are not necessary or preferred for centering content. The center environment and \centering command offer simpler methods for centering elements without resorting to floats.

When to Avoid Floating Environments

Floating environments automatically position content within the optimal place in the document flow. However, this sometimes results in content appearing farther away from the textual reference than desired. Additionally, floats require more verbose LaTeX code to set up captioning and labeling. In situations where precise vertical position is not critical and captioning is not needed, using the center environment and \centering command can provide adequate centered formatting while keeping code simple.

Using \centering for Quick Centered Content

The \centering command is the easiest way to center an individual element. Adding \centering within a figure or table environment will center that float. However, \centering also works with non-floating environments like \begin{minipage} to easily center boxes and text. Since it is applied to the current environment, \centering must be reapplied whenever the enclosing environment changes.

The center Environment for Multi-Line Centered Text

The center environment provides centered formatting across multiple lines, eliminating the need to use \centering repeatedly. center will center all textual content enclosed until the closing \end{center}, spanning line breaks as needed. This makes center well-suited for captions, multiline equations, and blocks of text that need to be centered without floats.

Spacing Around Centered Elements

Adding Vertical Space Before and After

LaTeX determines spacing before and after environments based on defined rules for each element. To override the default spacing, special commands can add extra vertical whitespace.

\vspace{length} inserts implied vertical space, pushing the subsequent content down. \vfill achieves a similar effect, stretching the blank space to fill all remaining vertical room on the page. These can be used before centered content to separate it from preceding text.

The \vspace* variant prevents automatic elimination of redundant spacings when multiple \vspace commands would result in overlapping whitespace. \vspace* ensures each specified spacing is applied independently.

Example Code for Centered Images

Images provide a straightforward use case for LaTeX's centering functions:

\begin{center}
  \vspace{12pt} 
  \includegraphics[width=0.8\textwidth]{sample_image}
  \captionof{figure}{Image caption text} 
  \vspace{6pt}
\end{center}

This example applies 12 points of space before the graphic to separate it from earlier content. The \includegraphics command inserts the image scaled to 80% of the text width. Using \captionof provides a centered italic caption without needing to set up a full figure float environment just for centering. Finally, 6 points of space are inserted after the caption to add a bit of separation.

Example Code for Centered Equations

For aligning multiline equations, the equation environment is preferable to figure floats. center makes it easy to achieve the desired centering:

\begin{center}
  \vspace{12pt}
  \begin{equation}
    x = \frac{-b \pm \sqrt{b^2-4ac}}{2a} 
  \end{equation}
  \vspace{6pt}  
\end{center}

As with images, vertical space before and after separates the equation from surrounding text. The equation will span multiple lines while maintaining perfect center alignment.

Example Code for Centered Text Blocks

The center environment can also apply centering across blocks of text paragraphs:

\begin{center}
  \vspace{12pt}
  \begin{minipage}{0.8\textwidth} 
    This is a test paragraph spanning multiple lines, centered on the page.
    Line breaks will occur automatically based on the specified width...
  \end{minipage}
  \vspace{6pt}
\end{center}  

Here a minipage container sets strict horizontal width, causing automatic line wrapping within the enclosed paragraph. The surrounding center tags center the entire text block spanning multiple lines.

Achieving Consistent Style and Layout

Following best practices for applying vertical spacing, textual width constraints, and proper environment nesting results in professional, polished centering without dealing with floats. The techniques demonstrate how basic LaTeX building blocks combine flexibly to format centered content elements with consistency.

Summary of Best Practices

  • Use center rather than figure floats when precise vertical position is not required
  • Apply \vspace before and after to tune separation of centered elements from text
  • Set explicit textual widths with \textwidth or minipage for automatic line wrapping
  • Nest content like captions in the appropriate enclosing environments

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