# mesh-partition v3.2.3

**Mercurial revision 5786:5c8b45563631 | 2026-08-04**

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## Description

`mesh-partition` is a tool that uses the **METIS 4.0** program to partition a mesh. It is designed to work with **METIS 4.0**, so compatibility errors may occur with newer versions of METIS.

---

## Usage

```bash
mesh-partition [OPTIONS] -m input
```

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## Options


| Option                | Description                                                              |
| --------------------- | ------------------------------------------------------------------------ |
| `-h`, `--help`        | Display this help message and exit.                                      |
| `-m <file>`           | **Required.** Input mesh file or element list.                           |
| `--metis-path <path>` | Path to the METIS programs directory. Default: `/home/softs/metis-4.0/`. |
| `--metis5`            | Use this flag if you have installed **METIS 5.x** instead of METIS 4.x.  |
| `-p <number>`         | Number of desired partitions. Default: `4`.                              |


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## Deprecated Options

> **Warning:** These options are **no longer supported** and may be removed in future versions.


| Option      | Description                                          |
| ----------- | ---------------------------------------------------- |
| `-o <file>` | Output file (deprecated).                            |
| `-z <zone>` | Pre-set zone to limit the working area (deprecated). |


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## Examples

### **Basic Usage**

Partition a mesh file into 4 parts using the default METIS 4.0 path:

```bash
mesh-partition -m input_mesh.nc
```

### **Custom METIS Path**

Specify a custom path for METIS programs:

```bash
mesh-partition --metis-path /custom/path/to/metis/ -m input_mesh.nc
```

### **Partition into 8 Parts**

Partition the mesh into 8 parts:

```bash
mesh-partition -m input_mesh.nc -p 8
```

### **Using METIS 5.x**

Use METIS 5.x instead of METIS 4.0:

```bash
mesh-partition --metis5 -m input_mesh.nc
```

### **Custom METIS Path with METIS 5.x**

Combine a custom METIS path with METIS 5.x:

```bash
mesh-partition --metis-path /custom/path/to/metis5/ --metis5 -m input_mesh.nc -p 6
```

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## Environment Variables

`mesh-partition` relies on the **METIS** library. Ensure that:

- The METIS programs (`partnmesh` for METIS 4.x or `mpmetis` for METIS 5.x) are accessible via the specified `--metis-path`.
- The environment is configured to run METIS executables (e.g., `PATH` includes the METIS directory if not using `--metis-path`).

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## Notes

1. **Compatibility**:
  - This tool is **tested with METIS 4.0**. Using METIS 5.x requires the `--metis5` flag.
  - If you encounter errors, verify that the METIS version matches the flag used (`--metis5` for 5.x, no flag for 4.0).
2. **Input File**:
  - The input mesh file (`-m`) must be in a **supported format** (e.g., NetCDF or element list).
  - If the file cannot be read, the tool will exit with an error.
3. **Output**:
  - The partitioned mesh is saved as `mesh.metis.epart.<n>`, where `<n>` is the number of partitions.
  - The tool also generates intermediate files like `mesh.metis` for METIS processing.
4. **Performance**:
  - Partitioning large meshes may require significant memory and CPU resources.
  - Adjust `-p` based on the size of your mesh and available computational resources.

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## See Also

- [METIS Documentation](http://glaros.dtc.umn.edu/gkhome/metis/metis/overview) (for METIS 4.0 and 5.x)
- [METIS 5.x Release Notes](http://glaros.dtc.umn.edu/gkhome/metis/metis/download) (for compatibility details)