Physics 410: Computational Physics: Course News


This document will be updated throughout the course; entries are in reverse chronological order.

Tuesday, December 14, 2:00 PM

Here is the instructor suggested route to get from Hennings/old bus loop to the exam today, which will be held in CEME 1202. Note that the CEME bldg is basically surrounded by construction, so you'll have to detour a little to the east near the hospital as you make your way down East Mall (the fat vertical cyan line).

See y'all there.

PS: Note that it looks pretty stuffy over there; you might want to think about bringing water.

Click HERE for a printer friendlier version of the map.

Sunday, December 12, 4:15 PM

Three more items as we count down to the Great 410 Project Handin.
  1. The colour printer is now located in the Main Physics Office. Since this is, strictly speaking, out of bounds for undergraduates, undergrads can arrange to have me pick up color printouts of their term projects from the office. Let me know if you wish to avail yourself of this opportunity. Alternatively, if you know a grad student, they should also be able to pick it up for you.

    To print to the colour printer, log into physics and execute, e.g.

    	% lpr -Plp2 -Zsimplex your-project-name-here.ps
    	
    Please use -Zsimplex on whatever printer you use (again best to always print your final copy from physics, since that's where control of your printing is easiest), so that your term project is printed one-sided.

  2. Some of you have encountered problems in starting up xvs or DV when some other user is already using the application on whatever machine you are logged into. This occurs since by default, these applications use TCP/IP ports 5000 and 5005 respectively for communication, and as things are set up, a distinct port number is needed for each independent xvs or DV process.

    The solution to this problem is simply to choose another port number, and inform the application(s) that use this information (xvs, DV, sdftoxvs, sdftoDV etc. of the new choice. This is done via setting of the environment variables XVSPORT and DVPORT respectively. I suggest that you choose the port numbers simply by adding your userid (the third entry in /etc/passwd for your account name) to the default port numbers. For example, as you can verify by greping for 'matt' in /etc/passwd, matt's UID is 243. Thus I would set

    	setenv XVSPORT 5243
    	setenv DVPORT 5248
    	
    and, logically, place these lines in my ~/.cshrc file. (Please, please, don't put the above lines in YOUR ~/.cshrc. If 2 or more of you do so, you will defeat the disctinctiveness mechanism!!!).

    On the lnx machines, there are instructor-scripts getXVSPORT and getDVPORT that should be in your path, and that will return your UID added to 5000 or 5005 respectively, so that you can use

    	setenv XVSPORT `getXVSPORT`
    	setenv DVPORT  `getDVPORT`
    	
    Note that all of the quotes in the above are backticks, a.k.a. the most powerful punctuation known to humankind.

  3. I will do my best to keep the machines from hanging up in the wee hours of the upcoming morning, including coming into campus again if necessary. Contrary to Friday's diatribe, I now suspect that the problem is system-related, and if so, that's a BIG mea culpa!.

Thursday, December 9, 6:00 PM

Homework 5 has now been downloaded for grading, and Homework 5 keys are now available in the cardboard box outside by door.

We hope to be sending your grades/comments for Homework 4 by midnight tonight, and hope to do the same for Homework 5 by noon on Saturday.

Please remember that

  1. THE ABSOLUTELY-POSTIVELY-NO-EXCEPTIONS-BARRING-MAJOR-PERSONAL-EMERGENCY-DEADLINE for the TERM PROJECTS is NOON MONDAY DECEMBER 13.
  2. HARDCOPY of your term paper MUST be submitted to me, either in person (i.e. to my office), or to my mailbox in the main office. ELECTRONIC-ONLY SUBMISSIONS WILL NOT BE ACCEPTED. NO EXCEPTIONS, PLEASE!!

Tuesday, December 7, 11:30 AM

Nick Fameli has kindly passed along a course announcement of possible interest to some of you: Chem 507: Biomolecular Computer Simulation and Modelling taught by Chemistry's Walter Scott.

Saturday, December 4, 4:30 PM

Thanks to those of you who let me know via e-mail that sshd needed attention on the lnx machines. Connectivity to them should now have been restored.

Given the time of year, and in order to minimize frustration, from now until the exam, if you have problems accessing the course machines, you should feel free to phone me either at

  1. (604) 822-2412 (Work)
  2. (604) 222-9424 (Home)
Legitimate calls to either number will not lower your grade :-)

You can also continue to e-mail, and I will endeavour to try to keep things alive as much as possible.

Sorry again for the inconvenience caused earlier in the day.

Friday, November 26, 11:30 AM

I sure hope this is the last time I have to send a broadcast message about Homework 4.

However, I see that some folk other than the 555 registrants are attempting the whole assignment. Thus to minimize frustration, please note that the script lino alluded to in Problem 2e) should be lines. (lino is an antecedent of lines, with, as you may have discovered, a minimalist usage message.)

The online handout has again been updated.

Tuesday, November 23, 4:00 PM

In Problem 3 of Homework 4, Jon Benjamin has noticed a problem with the "template" definition of subroutine update4 in ~phys410/hw4/a3/diffusion4-priv.f, which was not modified appropriately following a cut-and-paste of the code for update2 from the previous question.

I have updated the aforementioned source file in ~phys410's account accordingly.

I once again apologize for any confusion this has called.

Monday, November 22, 11:00 PM

The fifth and final Homework handout is now available for download (and for debugging, of course!)

I will distribute hardcopies in tomorrow's class.

Monday, November 22, 5:00 PM

And another one.

Jason has found another typo in the Homework 4 handout. Equation (2.8) should begin


     n
  ( t , x )
         j

rather than

     n
  ( t , u )
         j

The online handout has again been updated.

Monday, November 22, 1:30 PM

The correction of typos continues!

Jon Benjamin has pointed out that in the source files ~phys410/hw4/a[23]/diffusion[24]-priv.f, the comment lines

c     u0(x) := u(t,0) = sin(2 Pi x)
should be replaced with
c     u0(x) := u(0,x) = sin(2 Pi x)
The on-line code has been updated accordingly.

Monday, November 22, 12:00 PM

Three additional items concerning the current homework handout:

Item 1

For problems 2a), 2b) and 3b), only the answers to the questions are needed in the worksheet; i.e. there is no need to provide any details re the derivation of your results, the worksheet simply serves as a convenient (I argue) way of electronically documenting your results.

Item 2

A student has brought to my attention a serious problem with exposition in Problems 2b) and 3b) of the current handout. Specifically, in the original handout I used the notation f_j for a generic quantity that appears on the right hand side of a linear system, i.e. I was asking you to cast the equations in the form

   C u = f

where C is a n x n tridiagonal matrix, u is the unknown vector, and f is the right hand side of the linear system that u satisfies.

Arguably (he pleads), for a physicist this is a good notation, since except at the boundaries we then have


   f  =  f(x )
    j       j

where one must understand that the f's that appear on the two sides of the above equation are NOT identical; one is the right hand side vector for a linear system satisfied by a particular vector, u, the other is a vector resulting from the "restriction" of a continuum function, f, to a vector of x-values, x.

Pedagogically, however, there can be NO argument that the original prescription left a lot to be desired! Thus, I have thus now modified the problem handout, as well as the template files ~phys410/hw4/a[23]/diffusion[24].mws so that you are now asked to set up a linear system of the form


   C u = b 

where C is a n x n tridiagonal matrix, u is the unknown vector, and b is the right hand side of the linear system that u satisfies.

Management should probably be horsewhipped, and apologizes profusely for the confusion that was caused.

Item 3

Another typo has been fixed in Problem 2e). Thanks, Tim.

The online handout has been updated to reflect all three of these items.

Sunday, November 21, 5:00 AM

Jason Penner has pointed out a typo in Problem 3d) of the current homework assignment. In the pseudo-code near the start of the sub-problem, the lines
   execute diffusion2  1 1 0.25 lambda 0 1
   execute diffusion4  1 1 0.25 lambda 0 1
should read
   execute diffusion2  6 1 0.25 lambda 0 1
   execute diffusion4  6 1 0.25 lambda 0 1
The on-line handout has been updated.

Sunday, November 14, 6:00 AM

Stefan Storey has pointed out another couple of typos in the current homework assignment, in equations (2.15) and (2.21) respectively. The on-line handout has been updated.

Saturday, November 13, 11:00 AM

Those of you who have neither downloaded the Homework 4 handout nor copied the hw4 subdirs from phys410@lnx1 can IGNORE THIS NEWS ITEM.

For those of you HAVE started the assignment, please note that I have made numerous typo-level modifications to the handout, as well as several small changes of various of the template files in ~phys410/hw4/a[23]. If possible, I would advise recopying any files that you have already copied from phys410, AFTER BACKING UP YOUR CURRENT WORK. You can then use, e.g. 'diff -r new-dir old-dir' to see the minor modifications in the template files.

Thanks to Jason Penner for pointing out a glitch in one of the template files.

Friday, November 12, 10:00 PM

Homework 4 is (finally) available for download via the course Homework page.

Don't be alarmed by the length of the handout. To a paraphrase an old adage, it hurt me a lot more than it's going to hurt you.

As always, let me know if you have any undue problems with the homework, or if you find bugs in the handout.

Monday, October 25, 8:30 AM

Jonathan Benjamin has pointed out the following typo in the current homework, Problem 3, Required Output section:
% Mandelbrot 500
should read
% Mandelbrot 501
The online version has been updated.

Thursday, October 14, 3:00 AM

Just a reminder that the term paper outlines are now due a week from today, Thursday, October 21, not Tuesday, October 19 as originally mandated.

Friday, October 8, 2:30 PM

The exam schedule is out, and our exam is scheduled for
   TUESDAY, DECEMBER 14 2004, 3:30 PM   LOCATION TBA
Let me know immediately if you have a conflict.

Thursday, October 7, 1:30 PM

The eagle-eyed Tian Si Wang and Daniel Eaton have both pointed out that the following excerpt from Problem 2 of Homework 2
    ... called ~/hw2/a3/procs.  I must be able to read ~/hw2/a3/procs ...
should read
    ... called ~/hw2/a2/procs.  I must be able to read ~/hw2/a2/procs ...
i.e. the answer to Problem 2 should live in directory ~/hw2/a2. The on-line version has been updated to reflect the bug-fix.

Friday, October 1, 1:30 PM

Jason Penner has found an on-line PDF version of The Maple 7 Programming Guide. I have added a link to it in the course Resources page, as well as on the Maple notes page, and you can also download it HERE.

The Guide is an updated version of the one whose first chapter I distributed to you, so those of you interested in the full details of Maple programming should find it quite useful.

Wednesday, September 29, 8:00 PM

Homework 2 is now ready for download, should you wish to take an advance look. I will distribute hardcopy in tomorrow's class.

Tuesday, September 21, 8:00 PM

See HERE for information on having your mail forwarded from your physics account.

Wednesday, September 15, 5:30 PM

We have burned several sets of the Mandrake 9.2.1 and Mandrake 10.0 installation CDs that class members are welcome to borrow on a first-come, first-serve basis. CDs are available from Matt's office, and can be picked up from there at your convenience (and after class in particular).

In deciding which of 9.2.1 or 10.0 (if either) you decide to install, note that 10.0 is, of course, the most recent version, but one with which Pal and I currently have no experience (i.e. we are somewhat more likely to be able to help you out with problems you have with 9.2.1).

Students who wish to avail themselves of this opportunity to install Linux on one or more home machines should feel reasonably comfortable with configuration of their PCs. Although the Mandrake distribution is quite user-friendly, and although installation of Mandrake on a system that already has a version of Windows installed should be straightforward in most cases (leaving you with a dual-boot system), there is still the possiblity that something could go awry, and that, e.g., you could end up trashing your Windows partition.

Best systems-administration practice dictates that one always make a complete backup of a system prior to commencing work such as Linux co-installation. I whole-heartedly commend this practice to you, and, unfortunately cannot except responsibility (nor can Pal) for any loss of data that may result from failed attempts to install Linux on Windows boxes.

Wednesday, September 15, 5:30 PM

The problem with KDE on lnx[12] should now be resolved.

Tuesday, September 14, 9:40 AM

The KDE windowing environment is currently not working properly on lnx1 and lnx2 and Pal and I are looking into the situation. In the meantime, should you encounter any problems working with KDE on the consoles of those machines, particularly in terms of how the windowing environment looks (i.e. cruddy fonts etc.), we suggest that you use Gnome.

Wednesday, September 8, 3:00 PM

IMPORTANT: Effective immediately, the class will meet in Hennings 318. This should ease the current overcrowding situation.

Tuesday, September 7, 9:00 PM

Jon Benjamin has discovered that physics.ubc.ca is not currently NFS-mounting lnx1.physics.ubc.ca:/home, lnx2.physics.ubc.ca:/home and lnx3.physics.ubc.ca:/home as described HERE (hardcopy of which was included in the first of the handouts covered today).

Darn, I thought I'd be able to sneak this one past you. This a matter out of the instructor's control, and a request has been made to remedy the situation. If all of this means nothing to you, with luck it will in a week or two.

Tuesday, September 7, 6:00 PM

I have created the following accounts on the lnx machines:
   dastegir    matthewe    jonben      tjblair     gbosdet     
   awbowie     wochao      szumeng     chin        manixc      
   rickychu    dhanesar    jwd         djeaton     fameli      
   lfan        pgf         jgallant    jgodfrey    benjamin    
   arefa       masrur      kasian      chinakt     bayo        
   lc          xiangli     mcliu       martham     tor         
   ajpenner    cpfuller    robinr      mayaro      rspence     
   sstorey     dongen      tswang      mandyman    wanyan      
   mencywoo    syewchuk    
If you wish, and if your account appears in the above list, you should now be able to ssh into the lnx machines from a remote host via any one of
   ssh userid@lnx1.physics.ubc.ca
   ssh userid@lnx2.physics.ubc.ca
   ssh userid@lnx3.physics.ubc.ca
where userid is to be replaced with your own user id. You should also be able to login into the lnx machines via their consoles in Hennings 205. Your password should be the same as that for your account on physics.ubc.ca. If you have any difficulties logging in, and if the NOTES concerning machine usage are not sufficient to solve these problems, let me know via e-mail immediately.

Sunday, September 5, 1:00 PM

Our first class is scheduled for 10 AM, Tuesday September 7, 2004 in Hennings 304.

As several of you are aware, the class is currently officially full. Should you still wish to register for the course, please send an email to the instructor, Matt Choptuik.