SExtractor uses an interpolated background for object detection and
either the same or a locally determined background for photometry (see
keyword BACKPHOTO_TYPE). But what is the background returned as the
output parameter BACKGROUND and subtracted from the image for the
output VIGNET?

BACKGROUND is the actual background used for photometry and selected
with BACKPHOTO_TYPE. The output VIGNET has the globally interpolated
background subtracted, however does not change if you use
BACKPHOTO_TYPE LOCAL. This is true as of version 2.8.6.

One stupid fact about multiplication with expr is that a simple '*'
won't work; you have to escape it as in

expr 3 \* 4

Ein Graphviz-Graph ist oft so
gross, dass er gar nicht sinnvoll auszudrucken ist. Mit der Zeile

page = "8.27,11.69"

innerhalb des digraph-Environments laesst sich die Ausgabe aber
automatisch in DIN-A4-Seiten (deren Groesse hier in Zoll angegeben
ist) aufteilen und so bequem ausdrucken und an die Wand kleben^.

This: http://www.ifp.illinois.edu/grouper/clapack.html
is a very helpful website for this daunting task.

This is how I got my unlocked, jailbroken iOS 3 iPhone 3GS (Model
MC135LL, Baseband 05.12.01) updated to iOS 4.1.

I first followed the instructions on
http://iphoneblogr.com/2010/11/redsn0w-0-9-6b2-tutorial-pwned-dfu-mode-for-windows-users/
to install the pro-broken iOS 4.1 from
http://iphoneblogr.com/2010/10/pre-jailbroken-4-1-firmware/

This resulted in a jailbroken 4.1 that was not, however, unlocked any
more. But the simple video tutorial
http://www.youtube.com/watch?v=VsQJdAjHnHE shows how to perform that
last step with ultrasn0w. It seems to work fine now!