====== Week 4 ======

~~NOTOC~~

===== Homework =====

  * Written HW: Ben-Ari p. 39: 
    * Exercises 2, 3, and 4
    * Due: today (11:59pm, if that helps)

===== Programming Assignment 2 =====

  * UPC Exercises 1.1 through 1.7
  * Due: Wed, Feb 20
  * Here's a link to a PDF of Ch. 1:  [[https://www.cs.vassar.edu/~cs377/private/|private]]
  * Hints
    * For timing your C/UPC programs, add the following to your code <code c>
      #include <time.h>
      
      int main()
      {
        clock_t startTime = clock();
        // your code to compute the C->F temperature conversions here
        // .
        // .
        clock_t endTime = clock();
        double cpuTime = ((double) (endTime - startTime)) / CLOCKS_PER_SEC;
        // print cpu time used
        // .
        // .
      }
      </code>
    * Here's another reference: \\ http://www.gnu.org/software/libc/manual/html_node/CPU-Time.html 

===== UPC =====

  * Unified Parallel C
  * see resources in sidebar
  * tutorial introduction


==== ssh keys ====
  * you need to set up your accounts for ssh'ing between workstations without password prompts
  * follow these steps to establish a trust connection for your account among our workstations
    - ''$ ssh-keygen'' \\ //hit enter through all the prompts//
    - ''$ cd ~/.ssh''
    - then type this command: <code text>$ cat id_rsa.pub >> authorized_keys</code>
  * for more information about ssh and public key authentication, see: [[wp>Secure_Shell]]

  * workstations in Asprey Lab: ''al101'' -- ''al124''
  * ssh into other workstations to test your ssh keys
    * first time you ssh to workstation you will be prompted to confirm it's okay: ''yes''
    * subsequent logins to that workstation should be without passwords or prompts!
    * this is what you need to do before attempting to run your UPC programs

==== setup ====
  * create a bin directory if you don't already have one:
    * ''$ cd''
    * ''$ mkdir bin''
  * copy my setup script into your bin directory:
    * ''$ cp ~mlsmith/bin/set-upc-env ~/bin''
  * run your setup script:
    * ''$ source ~/bin/set-upc-env''

  * copy the tutorial programs to your account under your course directory:
    * ''$ cd ~/cs377''
    * ''$ cp -r ~mlsmith/cs377-examples/upc ./'' \\ //this will create a ''upc'' directory under your course directory//
  * now you're ready to compile and run! (see sidebar [[tech_ref|technical reference]])

===== Lecture Notes =====

  * Ben-Ari Ch's 1 and 2
    * Ben-Ari slides: {{slides.pdf|PDF}}
      * resume slide 50
    * Formula(number of possible interleavings):
      * # interleavings = (nk)! / (k!)^n = $\frac{(nk)!} {(k!)^n}$ 
      * where n = # processes and k = # steps / process