Write a FORTRAN code to calculating factorials?

Answer 1

Here is a simple FORTRAN code to calculate the factorial of a given non-negative integer:

program factorial
    implicit none
    integer :: n, result

    print *, "Enter a non-negative integer:"
    read *, n

    result = 1
    if (n < 0) then
        print *, "Factorial is not defined for negative numbers."
    else
        do i = 1, n
            result = result * i
        end do
        print *, "Factorial of", n, "is", result
    end if
end program factorial

This program prompts the user for an integer, checks if it's non-negative, and then calculates the factorial using a loop.