Literal constants for KIND are semantically non-portable

[ThemosTsikas]

Hello,
I see you use "Real(kind=8)" and similar a lot. A real kind with value 8 might not exist on a compiler/machine, or might mean different things than what you seem to expect (an 8-byte real). The portable way to use KIND numbers is to ask the compiler, either via SELECTED_REAL_KIND/SELECTED_INT_KIND where you state your desired precision and range, or via the defined constants INT32/INT64/REAL32/REAL64 in intrinsic module ISO_FORTRAN_ENV where you state the storage size in bits needed.