Crashtestastronomer

Building my own guitar valve amplifier…

crashtestastronomer — Sun, 24 Apr 2011 22:11:04 +0000

Yes, I’m doing it. I’ve decided to build one. Spend money on stuff, have fun putting them together, have fun using it. There’s an extra layer of fun in there

First thing I’m doing is using this schematic:

from which I am have created created this layout:

~~Its not done yet, but I’ll post progress here as I go along.~~
Its done now, just needs some final checking for mistakes.

If you spot a mistake or think the layout can be improved in any way, please shout.

cheerio

Tagged: 18 watt, 1974x, amplifier, clone, DIY, EL84, electric guitar, layout, lite iib, marshall, Push-pull, schematic, superlite, tube, valve

Working on a little something on the side

crashtestastronomer — Wed, 13 Oct 2010 15:37:13 +0000

I’ve always wanted to make a game. Seeing I like flight simulators I though a flying game will be just the thing. Turns out its rather difficult and the amount of free game art available isn’t THAT inspiring so I decided to learn to do it all myself, at least until the first simple demo works. Seeing that I’m South African and our airforce used Mirage fighters for a long time, I decided to make a flying game featuring a Mirage F1 jet. Here’s a pic of my Blender model as it stands now:

: Here’s what my model looks like now.

As for the game, I decided to do it in Python using the Panda3d engine. I’ve got a very basic toy flying around a simple map at the moment. I’m still figuring out how to make certain components work e.g. the flight model, which I have running using JSBSim and its python bindings as well as how to make large terrains without bringing my laptop to a halt. I need to add collisions and all that too.

The next big problem will be the development of a believable flight model for my Mirage. There isn’t one on Flightgear I can borrow so I’ve decided to make one using the “datcom” program. But thats for another day…

Tagged: Blender, datcom, JSBSim, Mirage, Panda3d, python

Deeming periodogram codes on github

crashtestastronomer — Wed, 04 Nov 2009 23:33:33 +0000

I’ve uploaded the previous post’s source code to github.
Get it at http://gist.github.com/226473

Tagged: astronomy, cython, f2py, fortran, fourier transform, lightcurves, numpy, periodogram, python

Using a multithreaded Fortran module in python using f2py.

crashtestastronomer — Thu, 30 Jul 2009 17:30:29 +0000

This is something I’ve been wanting to do for a while and TODAY I GOT IT WORKING! This is an example of using a multithreaded fortran subroutine in python. I created the wrapper using the fantastic f2py. The multithreading is done using the OpenMP library. The example calculates a discrete fourier transform using a brute force approach. It may not be the best algorithm but it works. The DFT works for unevenly sampled data and in astronomy we use it often to look for periodicities in the time-series observations we make of variable stars.

Here is all the codes you need to make it work, hopefully I use Ubuntu Linux 8.10 64bit. You’re on your own if you use windows, I don’t ever use it so I don’t know how to make these things work.
Save the fortran file as periodogram.f90. Also save the python file into the same directory. Then, inside that directory, run the command “f2py -c -m deemingomp periodogram.f90 –f90flags=”-fopenmp ” -lgomp”. Then run the python script.

I get the following output on my laptop with a Core 2 Duo 2.5 GHz processor:

ewald@ewald-laptop64:/media/bigdrive/programming/f2py_omp/ompdft$ python deeming.wordpress.py
Python version : 3.27098703384
Fortran 90 version : 1.31940603256
Fortran 90 OpenMP version : 0.72838306427
ewald@ewald-laptop64:/media/bigdrive/programming/f2py_omp/ompdft$

and this is on my Core 2 Quad Q8200 desktop:

ewald@viper:~$ python deeming.wordpress.py
Python version : 3.67803311348
Fortran 90 version : 1.50673294067
Fortran 90 OpenMP version : 0.393154859543
ewald@viper:~$

The speed-up using 2 or 4 cores is pretty good. To run this example you’ll need numpy (which comes with f2py) as well as a fortran compiler (I use gfortran from the Ubuntu repos).

Have fun!! Any comments on how to make this better are definitely welcome.

Edit: I’ve removed the code from the page, check the next post for the github link to where it is available.

Tagged: f2py, fortran, openmp, parallel, performance, processing, python

Ubuntu vs Dell Optiplex 760

crashtestastronomer — Wed, 22 Jul 2009 13:33:03 +0000

At last I recieved a desktop computer at the observatory where I’m a student. Its a brand new Dell Optiplex 760 with a Core 2 Quad Q8200 with 4GB of ram. We ordered it without an OS (Because you can choose between Windows and Windows and astronomers don’t use that) so I took to the task of installing Ubuntu on it. In order to squeeze that last bit of performance out of the system I decided to install a 64bit variant. I’ve been running Ubuntu 8.10 64bit on my XPS M1530 for almost a year now without major problems so I assumed it would be fine.

The first attempt was with 8.04.3 64bit. The live disk started but the network adaptor and the display wasn’t detected properly. I decided hardy was too old for this desktop. This pretty much left 8.10 because I still can’t get pyraf 1.8 to run in 9.04 under python 2.6. If you know how to get this running without using multiple python installations PLEASE let me know.

Ubuntu 8.10 64bit was the winner. Everything worked first time. The desktop effects even worked by default (The computer has the onboard Intel gfx chip).

Wow. This machine is really quiet and even under a full load (4 cores running at 100%) the cpu temperatures stay below 50 degrees centigrade. Not too bad methinks. The 22″ 2209WA also helps in making my computing experience enjoyable

Tagged: Dell, iraf, linux, Optiplex, pyraf, python, Ubuntu, XPS M1530

Syntax highlighted Python code in a blog.

crashtestastronomer — Sun, 31 May 2009 00:07:30 +0000

OK, I give up. I don’t know how to format source code properly in this blog. Blech.

from numpy import arange,sqrt, random, linalg
from multiprocessing import Pool

global counter
counter = 0
def cb(r):
global counter
# print counter, r
counter =1

def det(M):
return linalg.det(M)

po = Pool(1)
for i in xrange(1,3000):
j = random.normal(1,1,(100,100))
po.apply_async(det,(j,),callback=cb)
po.close()
po.join()
print counter

First post at WordPress.

crashtestastronomer — Sat, 30 May 2009 23:22:16 +0000

I’ve decided to move away from blogspot and try out WordPress instead. So far so good. I’ll post things here about python, astronomy and everything else

Cheers.