To-Do

Derivatives

How to handle derivatives with types such as subset(variable)
Is it the best solution to store all different kind of constants in AllVars?
Need a assignment function for IsVarPointer --> than one can use Vec<double, VarPointer<decltype(av), 0, 0>, VariableTypeTrait> vp1(av) as normal variable

Types

does different types of vector work well together
remove not required traits

Required code

update all unary functions
update all binary functions
update subsetting
update interpolation
update helper
update printing