Objectives

The objective of this lab is to write your first MPI program, to debug and test it, and to experimentally determine the gains you get in running it in parallel on up to 16 processors (two nodes on bassi). Additionally, you will have two versions of your code: one using a block distribution and one using a cyclic distribution. The timings for both versions should be compared and discussed in your report.

Problem Statement

Exercise 4.11 in the text describes how the value of Pi can be computed by evaluating a definite integral. Your main assignment is to solve Problem 4.11. That is, turn in a correct working program that computes Pi using the rectangle rule. You should also address 4.11 (b) relating to the performance of your parallel program on a varying number of processors and report that in your lab report.

Your code should conform to the following:

• Your code should be parameterized with the number of strips to evaluate, i.e., it should run for any value from 1,000,000 to 10,000,000. Your program should take this value (the number of strips) as a command line argument.
• You should use a cyclic distribution of the computations to processors, as in the circuit satisfiability example in the text.
• Each process, after completing its share of computations should print, to the stdout, its processor id, followed by its partial sum (that it is going to return to the master process). Just print the "raw" partial result, do not multiply it by 4. Use the following format:

  	printf("%d %lf\n", rank, partial_result); 

  where, rank is the rank of the process, and partial_result is the result it has computed and is going to return to the master process.
• The master process (after adding up the partial results) should print the final Pi Value. Use the following format:

  	printf("FINAL PI VALUE IS %lf\n", final_result); 

  where, final_result is the final value of Pi computed by the master process.
• You should submit the C source code in a file named pi_cycle.c by Sept. 15, midnight.

What/When/How to Submit:

• Midnight, Tuesday, Sept 15. pi_cycle.c to be submitted via checkin as HW1. Instructions for turning in your tar file.
• 2:00 pm, Thursday, Sept 17. pi_block.c to be submitted via checkin as HW1_PART2. Lab report to be turned in (hardcopy) in class (distance students turn in their reports electronically using checkin as HW1_REPORT). If pi_cycle.c has been modified between submission of HW1 and the lab report, please turn in the new version also by checkin as HW1_PART2, and describe clearly in a README file included in the checkin, what has changed (also briefly discuss these changes in your lab report).

Good luck and have fun!