Key Points

Connecting to ARCHER2 and transferring data

  • We should all understand and follow the ARCHER2 Code of Conduct to ensure this course is conducted in the best teaching environment.
  • ARCHER2’s login address is login.archer2.ac.uk.
  • You have to change the default text password the first time you log in
  • MFA is mandatory in ARCHER2

Arrays

  • Fortran supports both static- and dynamic-sized arrays
  • Fortran arrays are objects, allowing out of bounds accesses to be checked
  • The bounds of an array can be set by the programmer

Break

Arrays as arguments

  • Arrays passed as arguments retain their size, not their bounds
  • Array arguments behave as though passed by reference, however array sections may require copy-in, copy-out

More on pointers

  • Fortran pointers describe what they are pointing to, not only its address.
  • We must take care when programming with pointers to avoid aliasing.
  • Procedure pointers create a binding between a variable and a procedure.

Lunch

Derived types

  • Derived types enable creating custom data structures in Fortran.
  • Access to components of derived types can be controlled via the private attribute.

Interfaces and overloading

  • Interfaces allow us to write generic, high-level code.
  • Designing a generic interface requires care, particularly for generic operators.

Break

Type extension and polymorphism

  • Fortran supports polymorphism through the class pointers and allocatable objects.
  • Types can be selected dynamically to support type-specific behaviours

Type-bound procedures

  • Type-bound procedures allow Fortran objects to implement behaviour
  • Redefining type-bound procedures allows behaviour to be specialised
  • Types can prevent extended types from redefining type-bound procedures
  • Generic type-bound procedures enable generic methods on types

Generic input/output for derived types

  • Defined types can control how they are printed using type-bound procedures

Abstract types

  • Abstract types allow Fortran programs to specify and use interfaces that are then provided by concrete implementations.

Break

Modules again

  • Submodules provide the mechanism to separate interface and implementation in Fortran

Unlimited polymorphic entities

  • Unlimited polymorphic entities provide a void *-like type in Fortran
  • Without determining the unlimite polymorphic entity’s dynamic type, it cannot be used

Lunch

Type parameters

  • The kind of a user-defined type must be known at compile time (as for intrinsic types)

Intrinsic modules

  • The iso_fortran_env intrinsic module provides constants and functions that enable code portability
  • The IEEE intrinsic modules allow programs to check the conformance with IEEE features

Break

Interoperability with C

  • The iso_c_binding module allows a programmer to write Fortran that is interoperable with C.
  • Care must be taken with pointers and arrays, and with variables which are to be passed to C by value.