Tag Archives: research

Searching for Nearest-Neighbors between Two Coordinate Catalogs

Say I have two catalogs of points, each in two-dimensional space. For each object in a catalog, I want to find the nearest object(s) in the other catalog. I can do this by computing the distances between every single unique … Continue reading

Posted in Uncategorized | Tagged , , , , | 2 Comments

g3data

This is all I needed to use this: Love Debian.

Posted in Uncategorized | Tagged , , , , , , , | Leave a comment

Half-Light Radii for Various Profiles

For a radial profile of , the enclosed flux within the radius is given by     I’m only concerned about azimuthal symmetric cases, so .  The idea is to solve     for . Gaussian Profile Say the Gaussian … Continue reading

Posted in Uncategorized | Tagged , , , | 5 Comments

SciPy Weave Bug in Debian Squeeze

I was trying to remove a bottleneck by converting a portion of Python code into C++ via scipy.weave.inline, and encountered a bug. Here is my code: And this is what I get: Fortunately there is a fix: The fix for … Continue reading

Posted in Uncategorized | Tagged , , , , , , | Leave a comment

Comparing the Efficiencies of Gaussian Convolution Routines

These days I quite often need to convolve (i.e., smooth) 2D images by some Gaussian. There are quite a few routines that can do this with varying efficiencies. So I compared a couple of them. On my laptop, this script … Continue reading

Posted in Uncategorized | Tagged , , , , , | Leave a comment

SExtractor on Debian Squeeze (AMD64)

Installing from Debian Repository $ sudo aptitude install sextractor This version is rather old (v2.4.4) though. Installing from Source I need FFTW and ATLAS installed already, and assume that FFTW was installed at /usr/local/fftw, and ATLAS at /usr/local/atlas following the … Continue reading

Posted in Uncategorized | Tagged , , , , , , , , | Leave a comment

FFTW on Debian Squeeze (AMD64)

Installing from Debian Repository $ sudo aptitude install libfftw3-3 libfftw3-dev The second package is only necessary for development. Installing from Source The version of FFTW I use here is 3.2.2.  Follow this: $ mkdir tmp $ cd tmp $ wget … Continue reading

Posted in Uncategorized | Tagged , , , , , , , , | 2 Comments

ATLAS on Debian Squeeze (AMD64)

Installing from Debian Repository $ sudo aptitude install libatlas3gf-base $ sudo aptitude install libatlas-base-dev The second line is necessary only for development. Installing from Source Disable CPU throttling.  Find out how many CPUs I have: $ cat /proc/cpuinfo … info … Continue reading

Posted in Uncategorized | Tagged , , , , , , , , | 3 Comments

Installing IRAF version 2.15 on Debian Squeeze

My way of installing IRAF v2.15, now 64-bit by default. First create a regular user named “iraf”: $ sudo adduser iraf $ sudo aptitude install csh $ sudo ln -s /usr/lib/libncurses.so /usr/lib/libtermcap.so.2 The second line installing csh is necessary because … Continue reading

Posted in Uncategorized | Tagged , , , , , , , | Leave a comment

Some Physics Units Cheat Sheet

Before I forget: In CGS:     where        

Posted in Uncategorized | Tagged , , , | Leave a comment