Siunitx, Tabular And Table-format - Rounding Does Not Work

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Introduction

When working with tables in LaTeX, it's essential to have precise control over the formatting and rounding of numerical values. The siunitx package is a popular choice for this purpose, offering a wide range of features and options for customizing the appearance of tables. However, users have reported issues with rounding not working as expected, particularly when using the table-format option. In this article, we'll delve into the details of this problem and provide a step-by-step guide to resolving it.

Understanding the Issue

The issue with rounding not working correctly is often related to the way siunitx handles numerical values. When you specify a table-format option, siunitx uses this format to determine how to display the numbers in the table. However, if the global round-precision is set to a value that is not compatible with the table-format option, rounding may not occur as expected.

Minimal Working Example (MWE)

To illustrate this issue, let's consider a simplified MWE from the siunitx documentation:

\documentclass{article}
\usepackage{siunitx}

\begin{document}


\sisetup{
round-mode = places,
round-precision = 2
}


\begin{tabular}{S}
\hline
123.4567 \
\hline
\end{tabular}


\end{document}

In this example, we've set the global round-precision to 2 using the \sisetup command. However, when we display the number 123.4567 in the table, it's not rounded to 2 decimal places as expected.

The Role of table-format

The table-format option is used to specify the format of the numbers in the table. For example, if we want to display numbers with 2 decimal places, we can use the table-format option as follows:

\documentclass{article}
\usepackage{siunitx}

\begin{document}


\sisetup{
round-mode = places,
round-precision = 2
}


\begin{tabular}{S[table-format=1.2]}
\hline
123.4567 \
\hline
\end{tabular}


\end{document}

In this example, we've added the table-format=1.2 option to the tabular environment. This tells siunitx to display numbers with 1 digit before the decimal point and 2 digits after the decimal point.

Resolving the Issue

So, what's the problem with rounding not working correctly? The issue lies in the fact that the global round-precision is set to 2, but the table-format option is set to 1.2. This means that siunitx is trying to round the number 123.4567 to 2 decimal places, but the table-format option is only specifying 1 digit before the decimal point.

To resolve this issue, we need to ensure that the global round-precision is compatible with the table-format option. In this case, we can simply change the global round-precision to 1.2:

\documentclass{article}
\usepackage{siunitx}

\begin{document}


\sisetup{
round-mode = places,
round-precision = 1.2
}


\begin{tabular}{S[table-format=1.2]}
\hline
123.4567 \
\hline
\end{tabular}


\end{document}

By setting the global round-precision to 1.2, we ensure that siunitx rounds the number 123.4567 to 1 digit before the decimal point and 2 digits after the decimal point, as specified by the table-format option.

Conclusion

In conclusion, the issue with rounding not working correctly in siunitx tables is often related to the way siunitx handles numerical values. By understanding the role of the table-format option and ensuring that the global round-precision is compatible with this option, we can resolve the issue and achieve the desired formatting and rounding of numerical values in our tables.

Best Practices

To avoid this issue in the future, follow these best practices:

  • Always specify the table-format option when using siunitx tables.
  • Ensure that the global round-precision is compatible with the table-format option.
  • Use the round-mode option to specify the rounding mode (e.g., places or figures).
  • Use the round-precision option to specify the number of decimal places to round to.

Q: What is the purpose of the table-format option in siunitx?

A: The table-format option in siunitx is used to specify the format of the numbers in the table. It allows you to control the number of digits before and after the decimal point, as well as the presence of a decimal point.

Q: How do I specify the table-format option in siunitx?

A: To specify the table-format option in siunitx, you can use the table-format key in the S column type. For example:

\begin{tabular}{S[table-format=1.2]}
  \hline
  123.4567 \\
  \hline
\end{tabular}

In this example, the table-format option is set to 1.2, which means that the numbers in the table will be displayed with 1 digit before the decimal point and 2 digits after the decimal point.

Q: What is the difference between round-mode and round-precision in siunitx?

A: The round-mode option in siunitx specifies the rounding mode, which can be either places or figures. The round-precision option specifies the number of decimal places to round to.

Q: How do I set the round-mode and round-precision options in siunitx?

A: To set the round-mode and round-precision options in siunitx, you can use the \sisetup command. For example:

\sisetup{
  round-mode = places,
  round-precision = 2
}

In this example, the round-mode option is set to places, which means that the numbers will be rounded to the specified number of decimal places. The round-precision option is set to 2, which means that the numbers will be rounded to 2 decimal places.

Q: Why is rounding not working correctly in my siunitx table?

A: There are several reasons why rounding may not be working correctly in your siunitx table. Some common issues include:

  • Incompatible table-format and round-precision options
  • Incorrect round-mode option
  • Missing or incorrect decimal point in the table-format option

Q: How do I troubleshoot rounding issues in siunitx?

A: To troubleshoot rounding issues in siunitx, you can try the following:

  • Check the table-format and round-precision options to ensure that they are compatible
  • Verify that the round-mode option is set correctly
  • Check for missing or incorrect decimal points in the table-format option
  • Use the \showoutput command to see the output of the table and identify any issues with rounding

Q: Can I use siunitx with other LaTeX packages?

A: Yes, siunitx can be used with other LaTeX packages, including tabular, array, and booktabs. However, you may need to adjust the options and settings to ensure compatibility.

Q: Are there any limitations to using siunitx?

A: Yes, there are some limitations to using siunitx. For example:

  • siunitx only works with numerical values, not with other types of data
  • siunitx requires a specific format for the numbers, which may not be compatible with all LaTeX packages
  • siunitx may not work correctly with certain types of tables or layouts

Q: How do I get help with siunitx?

A: If you need help with siunitx, you can try the following:

  • Check the siunitx documentation and user manual
  • Search online for tutorials and examples
  • Join a LaTeX community or forum to ask for help
  • Contact the author of siunitx directly for support