Erdarbeiten

If you are located behind a proxy server (or using TOR services) and running Leopard in combination with .Mac syncing, you might experience frequent crashes of the PubSubAgent. Here are a few links which provide a fix - in short: adding *.mac.com to the 'bypass proxies' list in System preferences → Network → Proxies.

More details here:
http://discussions.apple.com/thread.jspa?messageID=6056954
http://www.mmisoftware.co.uk/weblog/?p=293

Some more info on GMT's grdfft -T option from the GMT-Help archives :

> Dear GMT users,
> I am looking for more information about the grdfft -T option.
> 1) How does it decide where to use the water and infill densities?

From grdfft.c:
They get used in differences.
infill (ri) water (rw) load (rl) mantle (rm)
rigidity_d = (youngs_modulus *te*te*te)/(12.0*(1.0 - poissons_ratio*poissons_ratio))
d_over_restoring_force = rigidity_d/((rm -ri)*normal_gravity)
airy_ratio = -(rl -rw)/(rm -ri)

> 2) The example in the Reference manual pages uses -C4000. Does this mean 4km
> beneath the surface? This seems like an odd exercise, does anyone know a
> reason for this?
-C Upward (for zlevel > 0) or downward (for zlevel < 0)
continue the field zlevel meters.
The -C option is for upward or downard continuation of the field. -C4000
upward continues the field 4000 meters, which is about the depth of the ocean
in the example - so the output field should be as if it was at the surface of
the ocean.
> 3) How does it compare to other programs such as AIRYROOT?
No idea. Don't have "airyroot".
> 4) Any suggestions for references that explain this a bit further?
Geodynamics: Applications of continuum physics to geological problems
by Turcotte & Schubert, 1982, John Wiley, New York
(textbook for course in tectonophysics that I took a few years ago)

Ben Horner-Johnson

ps2pdf (Ghostscript) turns out to be buggy in some special cases where a landscape oriented GMT plot is converted to PDF. It just ignores the landscape orientation and makes a portrait one of it. This might be due to a bug in (an older version of) Ghostscript. Anyway, Apple's native version of ps2pdf "pstopdf" takes slightly longer in processing, but does the job correctly.

In order to get an inverted axis for xy plots use a minus sign in the -J option (scale/length of axis), e.g. -Jx-0.5/-1

After a head crash wiped out my Powerbook's hard disk a week ago, I was forced to re-install all the Unix software I had installed. This includes Python (an updated version compared to the Apple shipped one), GMT, and PostgreSQL/PostGIS. I used the new Python2.4.3 Universal Binary distribution from MacPython.org and ran into trouble (library linking/gcc) when I wanted to install other python modules.

So far so good. It took me a while to find the solution for this: As a good citizen I had installed the new XCode 2.3 update from the ADC which is all set up for the universal binary Intelmania shebang but forgot to tick the "Mac OS X 10.4 Universal SDK" option when customizing my XCode install. Apparently Universal MacPython requires this SDK to be installed, as it instructs the linker and compiler to use this specific SDK. Case solved -- all modules compile fine after I installed the SDK. It might be a little bit more helpful to put a note on the MacPython website as people likely need to compile all sorts of different modules which are not yet available as nicely pre-compiled universal binary packages. Anyway - here's the link to the full blog entry: from __future__ import *.

I have managed to get my blog migrated to pyblosxom. Finally a proper software and less hassle than iBlog. And everything for free and Python powered!

Finally I managed to upgrade PostgreSQL and PostGIS on my two machines running Mac OS 10.4.5 (Dual G5 and G4 Powerbook 12'') over the last weeks and now I am running v8.1.2 and 1.1.1 with geos-2.2.1 and proj-4.4.9.
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Subversion is a revision control software like CVS. It allows you to keep track of changes you made to any project, either software projects, data projects or your thesis.

Good tutorial to set up svn on Mac OS X:
http://www.distracto.net
Subversion home page:
http://subversion.tigris.org
Pre-compiled binaries for Mac OS X on Martin Bott's homepage:
http://www.codingmonkeys.net/mbo