> For the complete documentation index, see [llms.txt](https://nelson-9.gitbook.io/nelson/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://nelson-9.gitbook.io/nelson/markdown/en/validators/mustbesparse.md).

# mustBeSparse

Checks that value is a sparse matrix or raise an error.

## 📝 Syntax

* mustBeSparse(var)
* mustBeSparse(var, argPosition)
* C++: void mustBeSparse(const ArrayOfVector& args, int argPosition)

## 📥 Input argument

* var - a variable: all supported types and classes that implement issparse method.
* argPosition - a positive integer value: Position of input argument.

## 📄 Description

mustBeSparse checks that value is a sparse matrix or raise an error.

## 💡 Example

```matlab
mustBeSparse(true)
mustBeSparse(eye(3, 4))
mustBeSparse(sparse(eye(3, 4)))
```

## 🔗 See also

[issparse](/nelson/markdown/en/types/issparse.md).

## 🕔 History

| Version | 📄 Description  |
| ------- | --------------- |
| 1.11.0  | initial version |


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