Homework assignment, 100 points (due in one week)

The program at http://www.drtak.org/teaches/ARC/cisp365/samples/factor.pas works, but it is inefficient. To be more specific, the subroutine find_factor_f_in_n searches for a prime factor from 2 every time.

Start with downloading the program from the link listed above. Similar to the previous homework assignment, you are to add parameters and turn find_factor_f_in_n into a function, however, there is a twist in this homework assignment.

Make the program more efficient by letting find_factor_f_in_n modify a variable, storing the prime factor, that belongs to the main program. To do this, you'll need to perform the following changes to the program:

• turn find_factor_f_in_n into a function
• specify the return value of the function
• add any necessary parameters to the function
• add any necessary local variables to the function
• change the main program so it calls the function (instead of a procedure)
• change the main program to pass the appropriate parameters
• remove one of the initializations from find_factor_f_in_n
• add the initialization to the main program

These are the absolute requirements of the homework assignment. If your program does not conform to all of these requirements, your assignment will receive 0 point.

• no global variable can be accessed from find_factor_f_of_n
• find_factor_f_of_n must be a function, not a procedure
• find_factor_f_of_n cannot print, it cannot contain write or writeln
• once the main program has found a prime factor $p$, all subsequent calls to find_factor_f_of_n cannot reexamine all prime factors that are less than $p$.
• only pass by reference when it is necessary, otherwise, pass by value (this means that if you pass by reference when you could have passed by value, points will be deducted!)
• the overall behavior (as far as input and output is concerned) must remain unchanged from the original program