Physics 410: Computational Physics: Course News


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

Wednesday, November 19, 5:45 PM

Those of you working on the Schrodinger equation as a term project should note that the previously version of democomplex.f was errant in stating that cmplx should be used to construct a complex*16 value from two real*8 expressions. Indeed, cmplx always returns a complex*8 value, and dcmplx should be used instead. For example
      complex*16  z

      z = dcmplx(cos(0.2d0),sin(0.2d0))
Thanks to Scott Webster for bringing this to my attention.

Thursday, October 16, 9:45 AM

The deadline for Homework 3 has been extended until 9:00 AM, Thursday, October 23.

Friday, October 3, 9:15 AM

Those of who install Mandrake 9.1 on your home machines, and then download the Intel C++ and Intel compilers for Linux may encounter a problem with the installation of the compilers. Specifically, following the initial blurb that results from starting the installation
your-machine% ./install
   You're using machine type--i686, kernel--2.4.21, and glibc--2.3.1.
   This product is supported for use with the following combinations.
    
       Machine Type                Kernel   glibc
    
   1.  IA-32                       2.4.x   2.2.5, or
       IA-32                       2.4.x   2.2.93, or
    
   2.  Itanium(R)-based system     2.4.x    2.2.4, or
       Itanium(R)-based system     2.4.x    2.2.5
    
   x.  Exit
   For an unsupported install, select the platform most similar to yours. 
if you select "1", then you may get the following error messages (or similar):
   ./install: line 567: 10232 Segmentation fault      (core dumped) $SCRIPT_DIR/chklic -a -q -f"$FLEXLM_FEATURE_NAME" -f"$FLEXLM_FEATURE_NAME"L -pi86_r -pit64_lr -c"$LICENSE" >&$TEMPFILE.chklic.out
   ./install: line 567: 10233 Segmentation fault      (core dumped) $SCRIPT_DIR/chklic -a -q -f"$FLEXLM_FEATURE_NAME" -f"$FLEXLM_FEATURE_NAME"L -pi86_r -pit64_lr -c"$LICENSE" >&$TEMPFILE.chklic.out
   A valid FLEXlm license is required to install this product, but none were found
   in $INTEL_LICENSE_FILE (.:/opt/intel/licenses).
   Where is a valid FLEXlm license for this product?
even if you have installed the license(s) that was (were) mailed to you in the installation directory, or /opt/intel/licenses.

The problem appears to be with the executable chklic, which checks to see that a valid license is available, and can be circumvented by hacking on the install script. At (or near) line 111 of the script, are the following lines:

   $SCRIPT_DIR/chklic -a -q -f"$FLEXLM_FEATURE_NAME" -f"$FLEXLM_FEATURE_NAME"L -pi86_r -pit64_lr -c"$LICENSE" &> $TEMPFILE.chklic.out
   CHKLIC_EXIT=$?   
Comment out those lines, and insert the statement CHKLIC_EXIT=10 as follows:
#  $SCRIPT_DIR/chklic -a -q -f"$FLEXLM_FEATURE_NAME" -f"$FLEXLM_FEATURE_NAME"L -pi86_r -pit64_lr -c"$LICENSE" &> $TEMPFILE.chklic.out
#  CHKLIC_EXIT=$?   
   CHKLIC_EXIT=10
The install script should then work normally.

Thursday, October 2, 5:30 PM

Those of who would like to install Maple on your home machine(s) can see Mary Ann Potts in Hennings 203A to get the software.

Tuesday, September 30, 6:00

As Scott Webster suggested in today's class, the Maple construct
   [seq(subs(x=i,res1),i=0..3)];
in the polyinterp usage examples handout can be equivalently replaced with the simpler
   [seq(res1),x=0..3];

Tuesday, September 30, 4:30 PM

I now have two sets of CDs for Mandrake 9.1 in my office that are available for borrowing on a first come-first serve basis. In addition, as discussed in class, I have other software that you may also borrow to aid in the installation process.

Tuesday, September 23, 6:00 PM

Bruno Mundim has pointed out a minor typo in the Homework 2 handout. Specifically, in part 2 of Problem 3, the description should read
   whose i-th element is the 2-element list [ l1[i] , l2[i] ].
instead of
   whose i-th element is the 2-element list [ l1[1] , l2[i] ].
The handout has been updated to reflect this change.

Tuesday, September 16, 2:00 PM

In response to a question rasied in class today concerning the scoping of the special script variable, $0, the construct does indeed evaluate to the name of the function when used within the body of the function, as the following example illustrates:
lnx1% cat arg0
#!/bin/sh
 
fcn () {
   echo "In function foo: Argument 0='$0'"
}
 
echo "In main body of script: Argument 0='$0'"
fcn

lnx1% arg0
In main body of script: Argument 0='arg0'
In function foo: Argument 0='fcn'

Monday, September 15, 2:00 PM

Ryan McKenize has pointed out that users whose physics accounts predate August 2003, are likely to see certain diagnostic/error messages when they log into lts1, e.g.
lnx1% ssh choptuik@lts1
Linux lts1 2.4.21-2-686-smp #1 SMP Sat Jul 5 01:42:22 EST 2003 i686 GNU/Linux
 
The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.
 
Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Mon Sep 15 08:54:08 2003 from warp.physics.ubc.ca
/usr/ucb/tset: Command not found.
biff: Command not found.
These error messages arise from execution of the commands in ~/.login, which, like those in ~/.cshrc.user, are tailored to the Sun environment, and not to Linux.

For those of you encountering such messages, I suggest the insertion of the following lines at the beginning of your ~/.login on physics/lts1, (NOT on the lnx machines).

if ( `hostname` != physics ) then
   exit
endif
This will effectively disable execution of the ~/.login commands when you login to lts1, which, as discussed in the Unix notes, is a completely reasonable thing to do (i.e. there is no fundamental problem in having all of the C-shell start-up commands in ~/.cshrc).

The on-line Unix notes have been updated accordingly

Friday, September 12, 9:30 PM

Scott Webster has pointed out a minor typo in the the Homework 1 handout, that has now been corrected. Specifically, in Problem 7, the text following Some usage examples should make the operation of Rcp clear should (and now does) read:
% ls
a-dir/ a-file
The handout has been updated to reflect this change.

Thursday, September 11, 9:30 PM

To follow up on a question asked in class today concerning the use of a shell-variable evaluation in the context of a regular expression being passed to, e.g. grep, the approach that I suggested will indeed work, as the following example illustrates:
% cat foo
the
the the
$b
$b $b
''
'' ''

% set a='the'
% grep -n '^'$a'$' foo
1:the

% set a='$b'
% grep -n '^'$a'$' foo
3:$b

% set a="''"
% grep -n '^'$a'$' foo
5:''

Note that in the second and third invocations of grep above, $a evaluates to a string that contains shell-special characters, but that those characters are NOT interpreted by the shell; i.e. there is only a single level of evaluation by the shell of expressions typed at the command prompt.

Monday, September 8, 2:30 PM

I have created the following account on the lnx machines:
   kubanek
See the news item from Tuesday, September 2, for further information concerning the use of this account.

Sunday, September 7, 6:30 PM

I have created the following accounts on the lnx machines:
   mashumba  jhomenuk  geraldli  motamedm  orost
   roland    cweigand  berniew
See the news item from Tuesday, September 2, for further information concerning the use of these accounts.

Thursday, September 4, 8:30 AM

If your name appears in the following list, please send me an e-mail message (choptuik@physics.ubc.ca) as soon as you have an account on physics.ubc.ca, telling me the name of said account, so that I can set up your account on the lnx machines.
   Maria Alexandrova
   John Homenuke
   Mary Motamedi-Tafrehsi
   Roland Stevenson
   Bernie Wong
The same will apply to any student who was not at the first lecture.

Wednesday, September 3, 2:30 PM

The handout for Homework 1 is now available. I will distribute hard-copy in tomorrow's class.

Tuesday, September 2, 4:00 PM

I have created the following accounts on the lnx machines:
   yiying    lfan      froese    isgill    waynesud
   dnleong   aliptak   dcmackay  danicawm  brianmar
   ryanmck   kevmitch  bruno     musson    kiri
   pleasanc  trees     dwschout  schultzi  ullisch
   swebster
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, August 24, 1:00 PM

Our first class is scheduled for 10 AM, Tuesday September 2, 2003 in Hennings 304.