CMP 426 Operating Systems Homework 0 Solution

Question 1 (Ro):

The Collatz conjecture concerns what happens when we take any positive integer n and apply the following algorithm:

n=

 

{n / 2 , if n is even

 

3 * n + 1 , if n is odd

 

The conjecture states that when this algorithm is continually applied,

all positive integers will eventually reach 1. For example, if n = 35, the

sequence is

35, 106, 53, 160, 80, 40, 20, 10, 5, 16, 8, 4, 2, 1

 

Write a C program using the fork() system call that generates this

sequence in the child process. The starting number will be provided

from the command line. For example, if 8 is passed as a parameter on

the command line, the child process will output 8, 4, 2, 1. Because the

parent and child processes have their own copies of the data, it will be

necessary for the child to output the sequence. Have the parent invoke

the wait() call to wait for the child process to complete before exiting

the program. Perform necessary error checking to ensure that a positive

integer is passed on the command line.

File: question1.c

Language: C

Question 2 (Daniel):

Write a multithreaded program that outputs prime numbers. This

 program should work as follows: The user will run the program and

 will enter a number on the command line. The program will then create

 a separate thread that outputs all the prime numbers less than or equal

 to the number entered by the user. (You can use Java or C)

File: question2.java

Language: JAVA

Question 3 (Jordan):

Write a multithreaded program that calculates various statistical values

 for a list of numbers. This program will be passed a series of numbers on

 the command line and will then create three separate worker threads.

 One thread will determine the average of the numbers, the second

 will determine the maximum value, and the third will determine the

 minimum value. For example, suppose your program is passed the

 integers:

 

 

 90 81 78 95 79 72 85

 

 

 The program will report

 The average value is 82

 The minimum value is 72

 The maximum value is 95

 

 

 The variables representing the average, minimum, and maximum values

 will be stored globally. The worker threads will set these values, and the

 parent thread will output the values once the workers have exited. (We

 could obviously expand this program by creating additional threads

 that determine other statistical values, such as median and standard

 deviation.) (You can use Java or C)

File: question3.java

Language: JAVA

Question 4 (Alex):

The Fibonacci sequence is the series of numbers 0, 1, 1, 2, 3, 5, 8, ....

 Formally, it can be expressed as:

 f ib0 = 0

 f ib1 = 1

 f ibn = f ibn−1 + f ibn−2

 Write a multithreaded program that generates the Fibonacci sequence.

 This program should work as follows: On the command line, the user

 will enter the number of Fibonacci numbers that the program is to

 generate. The program will then create a separate thread that will

 generate the Fibonacci numbers, placing the sequence in data that can

 be shared by the threads (an array is probably the most convenient

 data structure). When the thread finishes execution, the parent thread

 will output the sequence generated by the child thread. Because the

 parent thread cannot begin outputting the Fibonacci sequence until the

 child thread finishes, the parent thread will have to wait for the child

 thread to finish. Use the techniques described in Section 4.4 to meet this

 requirement. (You can use Java or C)

File: question4.java