is there a FORTRAN-keyword similar to the __attribute__((vector)) of __declspec(vector) in C/C++,
which automatically creates a vectorized version of my function?
Fortran has elemental functions - you precede the FUNCTION keyword with the keyword ELEMENTAL. This is not really the same as __declspec(vector), but the Intel Fortran compiler is very good about vectorizing array and loop operations.
If you have further questions about Intel Fortran, please ask in one of our Fortran forum sections.