Hello noname,
It seems that you call that command in your home directory while the sources are not in /home but somewhere else.
In the installation instructions it says that you should do
Code:
git clone https://github.com/ngsxfem/ngsxfem.git
cd ngsxfem
mkdir build
cd build
before executing the cmake-command. Note that you are in a build directory then and ../ refers to the source of ngsxfem so that cmake can find the CMakeLists.txt file.
Please check where you downloaded ngsxfem and make sure that you refer to the correct source directory. Then try again.
Best,
Christoph