Circular Definition Of \fontsize And \@setfontsize ?

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Introduction

In the realm of TeX and LaTeX, macros play a crucial role in defining and customizing various aspects of document formatting. Two such macros, \fontsize and \@setfontsize, are often used in conjunction with each other to set the font size and baseline stretch of a document. However, a closer examination of their definitions reveals a seemingly circular relationship between them. In this article, we will delve into the definitions of these macros, explore their usage, and attempt to understand the underlying logic behind their circular definition.

Understanding the Macros

\fontsize

The \fontsize macro is defined as a long macro that takes two arguments, #1 and #2. When expanded, it calls the \set@fontsize macro, passing the baselinestretch value as an argument. The definition of \fontsize is as follows:

\expandafter\meaning\csname fontsize \endcsname

This expands to:

\long macro:#1#2->\set@fontsize \baselinestretch {#1}{#2}

As we can see, the \fontsize macro is essentially a wrapper around the \set@fontsize macro, passing the baselinestretch value as an argument.

\@setfontsize

The \@setfontsize macro is defined as a macro that takes three arguments, #1, #2, and #3. When expanded, it calls the \@nomath macro, passing the three arguments as an argument. The definition of \@setfontsize is as follows:

\expandafter\meaning\csname @setfontsize\endcsname

This expands to:

macro:#1#2#3->\@nomath #...

As we can see, the \@setfontsize macro is a more complex macro that takes three arguments and calls the \@nomath macro.

The Circular Relationship

At first glance, it may seem that the definitions of \fontsize and \@setfontsize are circular, with each macro calling the other. However, upon closer inspection, we can see that the \fontsize macro is actually a wrapper around the \set@fontsize macro, which is a different macro altogether.

The \@setfontsize macro, on the other hand, is a more complex macro that takes three arguments and calls the \@nomath macro. While it may seem that the \@setfontsize macro is related to the \fontsize macro, it is actually a separate macro with its own definition and purpose.

Usage and Example

So, how do we use these macros in practice? Let's consider an example:

\documentclass{article}
\begin{document}

\fontsize{12}{14} % Set the font size to 12pt with a baseline stretch of 14


This is a sample text.


\end{document}

In this example, we use the \fontsize macro to set the font size to 12pt with a baseline stretch of 14. The \fontsize macro is a wrapper around the \set@fontsize macro, which sets the font size and baseline stretch.

Conclusion

In conclusion, the definitions of \fontsize and \@setfontsize may seem circular at first glance, but upon closer inspection, we can see that they are actually separate macros with their own definitions and purposes. The \fontsize macro is a wrapper around the \set@fontsize macro, which sets the font size and baseline stretch accordingly. The \@setfontsize macro, on the other hand, is a more complex macro that takes three arguments and calls the \@nomath macro.

By understanding the definitions and usage of these macros, we can better appreciate the underlying logic behind their circular definition and use them effectively in our LaTeX documents.

Additional Information

For those interested in exploring the definitions of these macros further, the following commands can be used to extract the meaning of the macros:

\expandafter\meaning\csname fontsize \endcsname
\expandafter\meaning\csname @setfontsize\endcsname

These commands will expand to the definitions of the macros, allowing us to examine their structure and behavior in more detail.

References

  • The LaTeX Companion by Frank Mittelbach, Michel Goossens, Johannes Braams, David Carlisle, and Chris Rowley
  • The TeXbook by Donald E. Knuth
  • The LaTeX2e Sources by Leslie Lamport

Q: What is the purpose of the \fontsize macro?

A: The \fontsize macro is used to set the font size and baseline stretch of a document. It is a wrapper around the \set@fontsize macro, which sets the font size and baseline stretch accordingly.

Q: What is the difference between \fontsize and \@setfontsize?

A: While both macros are used to set the font size and baseline stretch, they are defined differently. The \fontsize macro is a wrapper around the \set@fontsize macro, whereas the \@setfontsize macro is a more complex macro that takes three arguments and calls the \@nomath macro.

Q: How do I use the \fontsize macro in my LaTeX document?

A: To use the \fontsize macro, simply include it in your LaTeX document, followed by the font size and baseline stretch values. For example:

\documentclass{article}
\begin{document}

\fontsize{12}{14} % Set the font size to 12pt with a baseline stretch of 14


This is a sample text.


\end{document}

Q: What is the purpose of the \@setfontsize macro?

A: The \@setfontsize macro is a more complex macro that takes three arguments and calls the \@nomath macro. Its purpose is not directly related to setting the font size and baseline stretch, but rather to perform other mathematical operations.

Q: Can I use the \@setfontsize macro to set the font size and baseline stretch?

A: No, the \@setfontsize macro is not intended to be used for setting the font size and baseline stretch. Its purpose is to perform other mathematical operations, and using it for this purpose may lead to unexpected results.

Q: How do I extract the meaning of the \fontsize and \@setfontsize macros?

A: To extract the meaning of the macros, use the following commands:

\expandafter\meaning\csname fontsize \endcsname
\expandafter\meaning\csname @setfontsize\endcsname

These commands will expand to the definitions of the macros, allowing you to examine their structure and behavior in more detail.

Q: What are some common use cases for the \fontsize macro?

A: The \fontsize macro is commonly used in LaTeX documents to:

  • Set the font size and baseline stretch for a specific section or chapter
  • Create custom font sizes and baseline stretches for a document
  • Adjust the font size and baseline stretch for a specific element, such as a table or figure

Q: Can I customize the behavior of the \fontsize macro?

A: Yes, you can customize the behavior of the \fontsize macro by redefining it or creating a new macro that builds upon its functionality. However, be aware that modifying the behavior of the \fontsize macro may affect the overall layout and formatting of your document.

Q: What are some common pitfalls to avoid when using \fontsize macro?

A: Some common pitfalls to avoid when using the \fontsize macro include:

  • Using the \@setfontsize macro to set the font size and baseline stretch, as this may lead to unexpected results
  • Failing to include the necessary packages or commands to use the \fontsize macro
  • Using the \fontsize macro in a way that conflicts with other LaTeX commands or packages

Q: Where can I find more information about the \fontsize and \@setfontsize macros?

A: For more information about the \fontsize and \@setfontsize macros, consult the following resources:

  • The LaTeX Companion by Frank Mittelbach, Michel Goossens, Johannes Braams, David Carlisle, and Chris Rowley
  • The TeXbook by Donald E. Knuth
  • The LaTeX2e Sources by Leslie Lamport

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