Fortran in a Nutshell

Introduction

Before Python, before C, before even Lisp, there was Fortran.

Yes, this is one of the oldest programming languages still in use today. Developed in the 1950s, Fortran (short for Formula Translation) was created to handle scientific and engineering computations—and it still does that job better than many modern languages.,

The History of Fortran

Fortran was born at IBM in 1957, thanks to John Backus and his team. At the time, programming was done in assembly language, which made writing complex calculations painfully slow and error-prone.

Why Was Fortran Created?

Scientists and engineers needed a way to write mathematical formulas in a human-readable way.
Computers were getting more powerful, but programming them was still a nightmare.
IBM wanted to make programming easier, and Fortran was their solution.

Key Innovations of Fortran

✅ First High-Level Language → Before Fortran, everything was hand-coded in assembly.
✅ First Compiler → The original Fortran compiler was one of the first optimizing compilers ever built.
✅ Built for Scientific Computing → Fortran was designed from day one for numerical computations.
✅ Still in Use Today → Modern Fortran (Fortran 90, 95, 2003, 2018) is used in climate modeling, physics, and engineering simulations.

Further Reading:
Fortran Wikipedia
The History of Fortran

Fortran’s Influence on Modern Languages

Feature	Fortran	Modern Equivalent
Mathematical Computations	✅ Yes	✅ Python (NumPy), Julia, MATLAB
Compiled Language	✅ Yes	✅ C, C++
High Performance	✅ Yes	✅ Rust, C++
Array Processing	✅ Yes	✅ Python (NumPy), R
Structured Programming (Introduced later)	✅ Yes	✅ C, Java, Python

💡 Verdict: Fortran is still one of the best languages for high-performance scientific computing!

Fortran Syntax Table

Concept	Fortran Code	Equivalent in Python / C
Hello World	`PRINT *, "Hello, World!"`	`print("Hello, World!")` / `printf("Hello, World!");`
Variables	`INTEGER :: x = 42`	`x = 42` / `int x = 42;`
Loops	`DO i = 1, 10` followed by `END DO`	`for i in range(1, 11):` / `for (int i=1; i<=10; i++)`
Conditionals	`IF (x > 5) THEN PRINT *, "High"`	`if x > 5: print('High')` / `if (x > 5) { printf("High"); }`
Functions	`FUNCTION square(x) RESULT(y) y = x*x END FUNCTION`	`def square(x): return x * x` / `int square(int x) { return x * x; }`
Arrays	`INTEGER, DIMENSION(5) :: A = (/1,2,3,4,5/)`	`A = [1, 2, 3, 4, 5]`
Modules (Introduced in Fortran 90)	`MODULE math_functions`	`import math`

10 Fortran Code Examples

1. Hello, World!

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PRINT *, "Hello, World!"

2. Declaring Variables

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INTEGER :: x = 42

3. If-Else Statement

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IF (x > 10) THEN
    PRINT *, "X is greater than 10"
ELSE
    PRINT *, "X is 10 or less"
END IF

4. For Loop

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DO i = 1, 5
    PRINT *, "Iteration:", i
END DO

5. Function Definition (Square Function)

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FUNCTION square(x) RESULT(y)
    INTEGER, INTENT(IN) :: x
    INTEGER :: y
    y = x * x
END FUNCTION square

6. Arrays

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INTEGER, DIMENSION(5) :: A = (/1, 2, 3, 4, 5/)

7. Reading User Input

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PRINT *, "Enter a number:"
READ *, x
PRINT *, "You entered:", x

8. Recursion (Factorial Function)

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RECURSIVE FUNCTION factorial(n) RESULT(fact)
    INTEGER, INTENT(IN) :: n
    INTEGER :: fact
    IF (n == 0) THEN
        fact = 1
    ELSE
        fact = n * factorial(n - 1)
    END IF
END FUNCTION factorial

9. Writing to a File

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OPEN(UNIT=10, FILE="output.txt", STATUS="NEW")
WRITE(10,*) "Hello, file!"
CLOSE(10)

10. Parallel Computing with OpenMP

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PROGRAM parallel_example
    USE OMP_LIB
    INTEGER :: i
    !$OMP PARALLEL DO
    DO i = 1, 10
        PRINT *, "Thread ", OMP_GET_THREAD_NUM(), " Processing ", i
    END DO
    !$OMP END PARALLEL DO
END PROGRAM parallel_example

Key Takeaways

Fortran is the first high-level programming language and is still in use today.
It remains the king of high-performance scientific computing.
Modern versions (Fortran 90, 95, 2003, 2018) are still evolving.
If you need to crunch numbers fast, Fortran is still one of the best options!