The Fortran 90 compiler is invoked, similar to any other compiler, by issuing a command with the name of the compiler, such as f90 <prog>, at the shell prompt. The NAG Fortran 90 compiler has several naming conventions that are useful. If the filename's extension ends with .f, it is assumed to be Fortran 77 source using its fixed source form. Using .f90 as the extension, it is assumed that the source file uses the free source form. These can be overridden using compiler switches and options. See the manual page for the f90 command for more details.
As a first attempt at using the Fortran 90 compiler, try the following exercise.
