Fortran (short for Formula Translation) is a high-level programming language designed for scientific and engineering applications. It was developed in the 1950s and is still widely used today in fields such as computational physics, chemistry, and engineering.
Here’s a crash course on Fortran:
- Basic syntax: Fortran code is divided into statements, which end with a semicolon (;). The first column of each line is reserved for line numbers, which are optional. Fortran is a free-form language, which means that whitespace and indentation don’t matter.
- Variables: Variables in Fortran are declared using the “type” keyword followed by the variable name. For example, to declare a variable x of type integer, you would use the following code:integer :: x
- Arithmetic operations: Fortran supports all the basic arithmetic operations, including addition (+), subtraction (-), multiplication (*), and division (/). There are also built-in functions for trigonometric, logarithmic, and exponential operations.
- Arrays: Arrays are collections of variables of the same type. In Fortran, arrays are declared using the “dimension” keyword. For example, to declare a 1D array of integers with 10 elements, you would use the following code:integer, dimension(10) :: my_array
- Control flow: Fortran supports standard control flow statements such as if-else and do-while loops. For example, here’s how you would use an if-else statement to print out whether a number is even or odd:if (mod(x, 2) == 0) then print *, “x is even” else print *, “x is odd” endif
- Subroutines and functions: Fortran allows you to define subroutines and functions, which are reusable blocks of code. Subroutines don’t return values, while functions do. Here’s an example of a function that calculates the factorial of a number:integer function factorial(n) integer, intent(in) :: n if (n == 0) then factorial = 1 else factorial = n * factorial(n-1) endif end function factorial
- Input and output: Fortran has built-in functions for input and output, such as print and read. Here’s how you would use print to display a message on the screen:print *, “Hello, world!”
- Modules: Fortran modules allow you to encapsulate related data types, procedures, and functions into a single unit. Modules can also be used for information hiding and abstraction. Here’s an example of a module that defines a simple data type:module my_module type :: my_type integer :: x real :: y end type my_type end module my_module
- Pointers: Fortran supports pointer variables, which allow you to create references to other variables or data structures. Pointers are commonly used in scientific and engineering applications to improve performance by avoiding unnecessary copying of data. Here’s an example of a pointer variable in Fortran:integer, target :: x integer, pointer :: ptr ptr => x
- Object-oriented programming: While Fortran is not typically thought of as an object-oriented language, it does have some support for object-oriented programming (OOP) through the use of user-defined types and polymorphism. Here’s an example of an OOP program in Fortran:
- type :: my_type integer :: x real :: y contains procedure :: print => my_type_print end type my_type
- interface subroutine my_type_print(this) import :: my_type class(my_type), intent(in) :: this end subroutine my_type_print end interface
- subroutine my_type_print(this) class(my_type), intent(in) :: this print *, “x = “, this%x print *, “y = “, this%y end subroutine my_type_print
- Parallel programming: Fortran supports various parallel programming models, such as OpenMP and MPI, which allow you to take advantage of multiple processors or cores to improve performance. Here’s an example of a simple parallel program using OpenMP:
- !$OMP PARALLEL print *, “Hello from thread “, omp_get_thread_num() !$OMP END PARALLEL
That’s a quick overview of Fortran. While Fortran is an older language, it’s still used in many scientific and engineering applications due to its performance and support for complex mathematical operations.
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