Lecture 18 gyrfalcON: Force Algorithm with Complexity O(N)

Physics 141/241

Winter 2020

Short article on gyrfalcON


Long article on gyrfalcON


gyrfalcON User Guide (updated)

describes gyrfalcON which is the executable code within the NEMO N-body system.

gyrfalcON mkgalaxy User Guide for creating galaxy with bulge and halo

gyrfalcON mkgalaxy script for creating disk galaxy with bulge and halo


Access to the source code of GyrflacON at /software/physics/nemo_cvs/usr/dehnen/falcON/

How to run gyrfalCOn from the NEMO system

The Nemo system is installed at /software/physics/nemo_cvs

If you are in your home directory switch to cshell by typing /bin/csh. The directory paths are set up by executing: source /software/physics/nemo_cvs/nemo_start which will set up all the required environment variables. In the case of trouble check whether the user environment variable NEMO is set to /software/physics/nemo_cvs (setenv NEMO /software/physics/nemo_cvs).

The command gyrfalcON with appropriate parameter inputs will run the code. For instructions, consult the User Guide and the manual page ( gyrfalcON). The file conversion programs are tabtos and snapprint, and the Aarseth to binary snapshot conversion is discussed in the ntmpv manual page.

Log of gyrfalcON test:

1 mkdir falcon-2019

2 cd falcon-2019

3 put your galaxy into the directory (or,we will create one later)

4 cp galaxy x.tab

5 gyrfalcON

6 echo $SHELL (make sure your shell in terminal window is changed to csh: /bin/csh)

7 source /software/physics/nemo_cvs/nemo_start

8 env

9 gyrfalcON

10 tabtos in=x.tab out=x.snap header=nbody,time block1=mass,pos,vel

11 ls

12 gyrfalcON in=x.snap out=xrun.snap tstop=10 Nlev=1 eps=0.01 kmax=3

13 ls

14 tsf xrun.snap

15 snapprint in=xrun.snap options=m,x,y,z,vx,vy,vz header=t > xrun.tab