Fractional difference method with scale dependent mesh, non-uniform mesh and uniform mesh

the code is for fractional equation with scale dependent mesh, non-uniform mesh and uniform mesh

Through the code, researchers can be familiar with fractional derivative equation soon. Here, we provide three kinds of mesh modes for fractional derivative equation. Also, it is for the article named "A scale-dependent finite difference method for time fractional derivative relaxation type equations". Some examples could be found from the paper to help to understand the codes.