Installing Eigen

Use PuTTY to log in to the server as the root user.
Run the following command to go to the Eigen installation directory:
```
cd /path/to/EIGEN
```
Run the following command to decompress the Eigen installation package:
```
tar -xvf eigen-3.3.7.tar.gz
```
Run the following command to switch to the directory generated after the package is decompressed:
```
cd eigen-3.3.7
```
Run the following command to create an include directory:
```
mkdir include
```
Run the following command to copy the Eigne directory to the include directory:
```
cp Eigen include -rf
```
Run the following command to obtain the Eigen absolute directory:
```
pwd
```

Parent topic: Configuring the Compilation Environment