k-d trees are useful data structures to store multidimensional points in such a way to preserve the relative position of the data points. Using this structure, we find all possible pairs of data points, distributed on a sphere, that are within a particular angular separation. We use the Astrometry.net spherematch package which is originally developed in C with a Python interface for astronomers. We introduce new functions in the level of Python-C extension of the package that enables us to use the power of OpenMP. We find that however adding more threads increases the efficiency of spherematch, the total run-time is dominated by other operations that need to be done in Python. Therefore, we implement the other intensive operations in C where we can also use OpenMP. This together with breaking the entire job into several smaller sub-tasks help of to reduce the run-time of individual sub-tasks, and therefore the total queue waiting time, that can dominate the total run-time.

The full report of this project is available in ehsan.ICS632.project.pdf.

Downloading Astrometry.net package we modified the following files and recompile the entire package:

URL: http://astrometry.net/downloads/

This is the directory where all the following files exist: astrometry.net-0.64/libkd

1. spherematch.py --> The higher level Python wrapper. It needs to import "spherematch_c" shared library

2. pyspherematch.c --> The wrapper Python-C extension

3. setup.py --> modified to include OMP flag, when compiling "pyspherematch.c" and producing "spherematch_c.so"

All other auxiliary Python codes to run tests and measure the performance:

1. ultra_test.py --> compares the original "spherematch.match" and Python implemented histogram code with "spherematch.match_sdr_omp" which performs all the necessary calculations in C.
2. pr.test1.py --> To measure the performance results for "spherematch.match_esn_omp"
3. pr.test2.py --> To measure the performance results for "spherematch.match_sss_omp"

Plotting the results: 4) test1.plot.py
5) test2.plot.desktop.py

• Copyright 2015
• Author: Ehsan Kourkchi ekourkchi@gmail.com