1. 1.To calculate the value of Pi,    we can use the graph of a circle and find the area under the graph.
2. 2.Riemann sum(https://en.wikipedia.org/wiki/Riemann_sum )is an effective method for finding the area under the graph
3. 3. Write a PThreads Program that will calculate Pi
   1.      -It should run 8 threads
   2.      -Create a global variable for the total sum 
   3.      -Use a Mutex variable to lock the critical section where you sum the results
4. 4.The program should output the sum at each thread and the parent will output the total sum
5. 5.Copy this version and remove the Mutex variable
   1.      -run both versions and compare the output
6. Need
   1. 1.Source Code
   2. 2.Screenshots of output of both programs

Some sample code for PThreads can be found here. https://grid.cs.gsu.edu/~cfrederick/csc4320/examples.php