How i include the ffmathlib Commnad on FreeFem++ data

Can you tell me how i include ffmatlib command to FreeFem++ codes. According to the online doccumentation of FreeFem++, i have included it but it showing error. Whether i have to install some packages for it.
matlab_octave_2d_examples.edp (1.3 KB)

Maybe you could look into the StabFem, which might give you some ideas how to use matlab or octave to postprocess the results.