# 'dmatrix' syntax

**URL:** <https://community.freefem.org/t/dmatrix-syntax/1791>\
**Category:** General Discussion\
**Created:** [May 30, 2022, 5:02pm UTC](https://community.freefem.org/t/dmatrix-syntax/1791 "2022-05-30T17:02:56Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Flavio](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/flavio/32/1178_2.png) [@Flavio](https://community.freefem.org/u/Flavio)\
**Post date:** [May 30, 2022, 5:02pm UTC](https://community.freefem.org/t/dmatrix-syntax/1791/1 "2022-05-30T17:02:57Z")

</div>

Hello,

I am trying to build a matrix, called **A** , which consists of blocks of smaller matrices along the diagonal and near-zero elements in the off-diagonal, in FreeFem v4.11 using the syntax:

```auto
dmatrix A(MatLinOp, clean=1, columns=Ji);

```

where `MatLinOp` specifies the blocks going into the diagonal of **A** , `clean=1` makes sure the near-zero elements are identically zero and `Ji` is just an index declaring the number of blocks going into matrix **A**.

If I execute this line in FreeFem v4.11, I get a compile error:

```auto
dmatrix The Identifier dmatrix does not exist
Compile error:
line number: 376, dmatrix

```

Is it because this syntax does no longer work in FreeFem v4.11?  
Any help is greatly appreciated.

---

<div class="post-metadata">

**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\
**Post date:** [May 30, 2022, 6:15pm UTC](https://community.freefem.org/t/dmatrix-syntax/1791/2 "2022-05-30T18:15:36Z")

</div>

`clean=1` does not do what you claim it is doing. `dmatrix` type has been deprecated/removed for at least 5 years. It is now simply `Mat`, as in PETSc.