Does anyone know whether it is possible to have an array that saves double precision variables in some columns and single precision in others columns? That is with out defining the whole array to save double precision numbers to save memory?
I am not clear as to what you want to do. I shall try to answer your question nonetheless.
Standard Fortran does not provide a way to create arrays whose elements have different types or kind type parameter values. The simple answer to your question thus is no. Oracle Solaris Studio Fortran and some other compilers implement union types as extensions to standard Fortran. Arrays of union types might provide the functionality you want, depending on what it is you want. My guess is that you will not be able to do what you want.