# Extra alignment tab has been changed to \cr

This error occurs when LaTeX is typesetting a table and detects an alignment character (`&`

) where it did not expect to find one. LaTeX uses alignment characters to separate table columns and will complain if a table tries to use more columns than expected.

## Error caused by the tabular environment

The tabular environment is a common source of this error, as demonstrated by the next example. Here, we have written `{c|c|c}`

to specify a table with three (centered) columns, meaning each table row should contain three cells.

```
\begin{tabular}{c|c|c} % Specify 3 centered columns
1 & 2 & 3 & 4\\ % ERROR: Uses 4 columns, not 3
5 & 6 & 7\\
\end{tabular}
```

Open this **error-generating** example in Overleaf

Our example generates the following error message:

and typesets this table:

### Explanation of the error

The first `&`

in a table row indicates the start of the *second* column; consequently, for a three-column table LaTeX expects to see *two* alignment characters before each line break (`\\`

). However, the first row of our table uses *three* alignment characters which confuses LaTeX, making it change the unexpected alignment character to the `\cr`

command—an attempt to reduce the number of columns to three. Note that using *three* alignment characters requires *four* columns.

### How to fix the error

To resolve this error and fix our table, we can either:

- remove the extra column by deleting the entry
- add an extra column to the tabular environment options (e.g., writing
`{c|c|c|c}`

) - create a new line (new table row)

Here is an example demonstrating each of these each solutions:

```
\section*{Removing the extra column entry}
\begin{center}
\begin{tabular}{c|c|c}
1 & 2 & 3\\
5 & 6 & 7\\
\end{tabular}
\end{center}
\section*{Adding an extra column to the tabular}
\begin{center}
\begin{tabular}{c|c|c|c}
1 & 2 & 3 & 4\\
5 & 6 & 7\\
\end{tabular}
\end{center}
\section*{Creating a new line (new table row)}
\begin{center}
\begin{tabular}{c|c|c}
1 & 2 & 3 \\
4 & & \\
5 & 6 & 7 \\
\end{tabular}
\end{center}
```

This example produces the following output:

## Errors caused by math environments

Mathematical typesetting often requires the alignment of math elements, which is achieved using environments such as `array`

, `matrix`

, and several others. Some math environments can trigger the extra alignment tab error because they use a table to perform their alignment, as demonstrated in the following examples.

### The array environment

LaTeX will generate an error if the number of alignment tabs used in an array row exceeds the number of array columns. Here is an example using an array with three columns but the first row tries to use four columns:

```
\[
\begin{array}{lcl}
g(x) & = & (x+2)^2 & = (x+2)(x+2)\\ % This row triggers the error
& = & x^2+4x+4\\
\end{array}
\]
```

Open this **error-generating** example in Overleaf

This example generates the following error message:

and typesets this array:

\[ \begin{array}{lcl} g(x) & = & (x+2)^2 \\ =(x+2)(x+2) \\ & = & x^2+4x+4\\ \end{array} \]

To correct this error, rewrite the array as follows:

```
\[
\begin{array}{lcl}
g(x) & = & (x+2)^2 \\
& = & (x+2)(x+2) \\
& = & x^2+4x+4\\
\end{array}
\]
```

Open this **corrected** example in Overleaf

The corrected array produces the following:

\[ \begin{array}{lcl} g(x) & = & (x+2)^2 \\ & = & (x+2)(x+2) \\ & = & x^2+4x+4\\ \end{array} \]

### The `amsmath`

matrix environments

The `amsmath`

package provides numerous environments for typesetting matrices, including `matrix`

, `pmatrix`

, `bmatrix`

, `Bmatrix`

, `vmatrix`

, and `Vmatrix`

.

The following `pmatrix`

example tries to use 12 columns but generates an error because `amsmath`

sets a default maximum of 10 columns in typeset matrices.

```
\documentclass{article}
\usepackage{amsmath} % To access the matrix environment
\begin{document}
\[
\begin{pmatrix}
a_{1,1} & a_{1,2} & a_{1,3} & a_{1,4} & a_{1,5} & a_{1,6} & a_{1,7} & a_{1,8} & a_{1,9} & a_{1,10} & a_{1,11} & a_{1,12} \\
\end{pmatrix}
\]
\end{document}
```

Open this **error-generating** example in Overleaf

To fix the error, change the column-maximum to 12 by writing `\setcounter{MaxMatrixCols}{12}`

, or any value of your choice.

```
\documentclass{article}
\usepackage{amsmath} % To access the pmatrix environment
\setcounter{MaxMatrixCols}{12}
\begin{document}
\[
\begin{pmatrix}
a_{1,1} & a_{1,2} & a_{1,3} & a_{1,4} & a_{1,5} & a_{1,6} & a_{1,7} & a_{1,8} & a_{1,9} & a_{1,10} & a_{1,11} & a_{1,12} \\
\end{pmatrix}
\]
\end{document}
```

Open this **corrected** example in Overleaf

The corrected example produces the following matrix:

\[ \begin{pmatrix} a_{1,1} & a_{1,2} & a_{1,3} & a_{1,4} & a_{1,5} & a_{1,6} & a_{1,7} & a_{1,8} & a_{1,9} & a_{1,10} & a_{1,11} & a_{1,12} \\ \end{pmatrix} \]

## A short note on the \cr command

LaTeX addresses the issue of an unexpected alignment character by substituting it with a fundamental command known as `\cr`

, which is integral to LaTeX's internal mechanics for concluding a table row. Although users utilize the LaTeX `\\`

macro to indicate the end of a table row, it is actually the `\cr`

command that is executed behind the scenes to terminate the row when the `\\`

macro is processed.

## Overleaf guides

- Creating a document in Overleaf
- Uploading a project
- Copying a project
- Creating a project from a template
- Using the Overleaf project menu
- Including images in Overleaf
- Exporting your work from Overleaf
- Working offline in Overleaf
- Using Track Changes in Overleaf
- Using bibliographies in Overleaf
- Sharing your work with others
- Using the History feature
- Debugging Compilation timeout errors
- How-to guides
- Guide to Overleaf’s premium features

## LaTeX Basics

- Creating your first LaTeX document
- Choosing a LaTeX Compiler
- Paragraphs and new lines
- Bold, italics and underlining
- Lists
- Errors

## Mathematics

- Mathematical expressions
- Subscripts and superscripts
- Brackets and Parentheses
- Matrices
- Fractions and Binomials
- Aligning equations
- Operators
- Spacing in math mode
- Integrals, sums and limits
- Display style in math mode
- List of Greek letters and math symbols
- Mathematical fonts
- Using the Symbol Palette in Overleaf

## Figures and tables

- Inserting Images
- Tables
- Positioning Images and Tables
- Lists of Tables and Figures
- Drawing Diagrams Directly in LaTeX
- TikZ package

## References and Citations

- Bibliography management with bibtex
- Bibliography management with natbib
- Bibliography management with biblatex
- Bibtex bibliography styles
- Natbib bibliography styles
- Natbib citation styles
- Biblatex bibliography styles
- Biblatex citation styles

## Languages

- Multilingual typesetting on Overleaf using polyglossia and fontspec
- Multilingual typesetting on Overleaf using babel and fontspec
- International language support
- Quotations and quotation marks
- Arabic
- Chinese
- French
- German
- Greek
- Italian
- Japanese
- Korean
- Portuguese
- Russian
- Spanish

## Document structure

- Sections and chapters
- Table of contents
- Cross referencing sections, equations and floats
- Indices
- Glossaries
- Nomenclatures
- Management in a large project
- Multi-file LaTeX projects
- Hyperlinks

## Formatting

- Lengths in LaTeX
- Headers and footers
- Page numbering
- Paragraph formatting
- Line breaks and blank spaces
- Text alignment
- Page size and margins
- Single sided and double sided documents
- Multiple columns
- Counters
- Code listing
- Code Highlighting with minted
- Using colours in LaTeX
- Footnotes
- Margin notes

## Fonts

## Presentations

## Commands

## Field specific

- Theorems and proofs
- Chemistry formulae
- Feynman diagrams
- Molecular orbital diagrams
- Chess notation
- Knitting patterns
- CircuiTikz package
- Pgfplots package
- Typesetting exams in LaTeX
- Knitr
- Attribute Value Matrices

## Class files

- Understanding packages and class files
- List of packages and class files
- Writing your own package
- Writing your own class