> If Fortran has been around for this long without a standard library, then what do people use now? The actual language, for example most of the functionality

> If Fortran has been around for this long without a standard library, then what do people use now? The actual language, for example most of the functionality that in C is considered to be in the standard library (like I/O operations, mathematical functions) is implemented in the language in Fortran's case. If the language is not enough for your particular case, you can use third party library like BLAS, LAPACK ...