# How to install and use FeynArts?

I want to be able to use both FeynCalc and FeynArts (together seems impossible, I'm fine with using them separately for now). I don't know how to install FeynArts and run the simplest examples. I tried Import["http://www.feyncalc.org/install.m"] which fetches FeynCalc and FeynArts but I cannot use this FeynArts for some reason. I cannot load it in Mathematica 10 (Mac OSX).

When I follow this site's suggestion

A dialog asking if you want to patch FeynArts will appear. Type yes and hit OK. Wait until the patching process finishes

This dialoge never appears in my case, but only an error message saying:

$LoadPhi = True;$LoadFeynArts = True; <<HighEnergyPhysicsFeynCalc;
Loading FeynCalc from /Users/MyName/Library/Mathematica/Applications/HighEnergyPhysics
FeynCalc 8.2.0 For help, type ?FeynCalc, open FeynCalcRef8.nb or visit www.feyncalc.org
Loading PHI
WARNING! Your FeynArts installation is not complete or the version you have cannot be used with this version of FeynCalc.
FeynArts can be downloaded at www.feynarts.de
Loading FeynArts, see www.feynarts.de for documentation
FeynArts not found. Please install FeynArts, e.g., in
/Users/MyName/Library/Mathematica
and reload FeynCalc
FeynArts can be downloaded from www.feynarts.de


Any suggestions?

• This seems like a duplicate of your earlier question. In what's sense do they differ? – Sjoerd C. de Vries Nov 16 '15 at 21:57
• No, now I'm already content with FeynCalc and FeynArts working separately. Of course it would be nice if they would be integrated... – Your Majesty Nov 16 '15 at 22:03
• Although I should add that I just (5 mins ago) plotted my first Feynman diagrams with FeynArts :D I've been struggling for 5-6 hours tried all possible routes until it worked. Also it seems they are working together now. – Your Majesty Nov 16 '15 at 22:04
• What I did was a mix of everything suggested here and there. Perhaps I'll make it an answer to this/the other thread tomorrow when I have my powers back. – Your Majesty Nov 16 '15 at 22:05
• For the latest version, open Mathematica and simply type: Import["https://raw.githubusercontent.com/FeynCalc/feyncalc/master/install.m"] InstallFeynCalc[InstallFeynCalcDevelopmentVersion -> True]  Finally if you want to patch FeynArts write the following $LoadFeynArts = True;  followed by <<FeynCalc (note there's a prime after FeynCalc! I cannot write it here though) – Your Majesty Nov 25 '15 at 13:00 ## 2 Answers Hmm, actually I thought that I wrote it in the wiki in a pretty clear way. For FeynCalc 9.0: https://github.com/FeynCalc/feyncalc/wiki/FeynArts#patching_fa2 For FeynCalc 8.2: https://github.com/FeynCalc/feyncalc/wiki/FeynArts#patching_fa FeynCalc 9.0 is still in development (Development version), but will be released until the end of this year. The GitHub repository is regularly updated with bugfixes. The installation is also quite straight forward https://github.com/FeynCalc/feyncalc/wiki/Installation#development_version This dialoge never appears in my case, but only an error message saying: This is because you applied the instruction for FC 9.0 to FC 8.2. No wonder that it didn't work. • Can one also use FormCalc with your solutions? I'm thinking about doing the examples found on this page: http://www.misho-web.com/phys/feynlecture.html eg. Lecture1-1.nb – Your Majesty Nov 18 '15 at 14:04 • FeynArts and FormCalc are fully compatible to each other, so no patching or any other modifications are needed to use them together. – vsht Nov 18 '15 at 15:45 • Actually your wiki is pretty good but in the jungle it's hard to know which one to follow so I followed multiple sources (as you pointed out) hence it was all a mess. But your wiki on the subject is sufficient, good job! – Your Majesty Nov 25 '15 at 12:59 Here's a short-worded solution for Mac OSX Mathematica 10. I am sure there are smoother ways to fix this but this worked for me: Autoinstall FeynCalc directly from Mathematica 10 by writing Import["http://www.feyncalc.org/install.m"]  This will create a directory in /Users/Yourname/Library/Mathematica/Applications. The name of the directory will be HighEnergyPhysics and it will contain a lot of files and other directories, including one called FeynArts-3.7. Now what I did was deleting this FeynArts-3.7 folder and replacing it with FeynArts-3.9 which you can download if you search the net for it. Following the instructions on the FeynArts.de page I saved a file called FeynInstall. Using the Terminal I made it executable by writing in the Mac terminal chmod 755 FeynInstall. The file that was created with this command I copied to the folder called /Users/Yourname/Library/Mathematica/Applications/HighEnergyPhysics/FeynArts-3.9. Finally I simply double clicked on FeynInstall and it asked me a bunch of question...I simply hit return until something happened. Now I restart Mathematica and write $LoadPhi = $LoadTARCER = False; followed by $LoadFeynArts = True; and then finally I write

<< HighEnergyPhysicsFeynCalc


A simple first example can go like:

CreateTopologies[1, 1->1];
Paint[%]
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