CSC 117 Programming for Scientists and Engineers

Project 7 Due: Monday, August 12, 2002

40 points

Please email the program to the grader by midnight on the due date.
You can use the command:
mail liuq@eng.unlv.edu -s "Project 7" < proj7.f90</tt>
where 'proj7.f90' is the name of the file you want to send.

(Problem 5, page 606 of your textbook.)
A prime number is an integer greater than 1 whose only positive
divisors are 1 and the integer itself. One method for finding all the
prime numbers in the range 2 through n is known as the Sieve of
Eratosthenes. Consider the list of numbers from 2 through n. Here 2
is the first prime number, but the multiples of 2 (4, 6, 8, ...) are
not, and so they are "crossed out" in the list. The first number
after 2 that was not crossed out is 3, the next prime. We then cross
out all higher multiples of 3 (6, 9, 12, ...) from the list. The next
number not crossed out is 5, the next prime; we cross out all higher
multiples of 5 (10, 15, 20, ...).   We repeat this procedure until we
reach the first number in the list that has not been crossed out and
whose square is greater than n. Write a program that uses this sieve
method to find all the prime numbers from 2 through n. Your program
should ask the user to input the value of n, a positive integer not
to exceed 4 digits.  Your program must use run-time arrays, and before
the program terminates, you must deallocate the run-time arrays to free
memory. Your output must look like the sample output shown below.  The
output should be on as many lines as necessary so that no output line has
length greater than 79.


Sample Output:

This program finds all primes from 2 through n.
Enter a positive value for n (not to exceed 9999): 100
Primes in the range 2 - 100 are:
    2    3    5    7   11   13   17   19   23   29   31   37   41   43   47
   53   59   61   67   71   73   79   83   89   97