dan hayes - 2014-04-28

wxMaxima version: 13.4.0
Maxima version: 5.31.1
Maxima build date: 2013-09-24 09:49:12
Host type: i686-pc-mingw32
Lisp implementation type: GNU Common Lisp (GCL)
Lisp implementation version: GCL 2.6.8

how does one use user contributed files - for example with extension .mac , bug in wigner_3j(...) and why it does not even appear in maxima help ?

While using windows explorer i noticed buried in \ProgramFiles(x86)\Maxima-5.31.1\share\maxima\5.31.1\share\contrib , which is unnecessary inconvenienc of which perhaps not all agree, but there should only be one directory maxima and put everything in that one directory instead of making all these subdirectories and subdirectories of subdir's etc.- everything would be so much simpler and direct if there was only ONE directory !!

Anyway found a file clebsch_gordan.mac so just out of curiosity did load(clebsch_gordan) on the command line in maxima and it seemed to take it with no error and all seemed ok. After looking at clebsh-gordan.tex, ...{Copyright 2007 by Edmond Orignac... , and found within that file

The Maxima function \texttt{wigner_3j(j1,j2,m1,m2,j,m)} computes the $3j$
coefficient of Wigner.

so now on maxima command line I do various possibilities and for most all the output is 0 when it should NOT be. For example wigner_3j(1,1,1,1,2,-2) should NOT be 0 as all would agree but it gives 0 as it does for most all other combinations which should not be zero.
Also whenever m1+m2+m#0 it should be 0 but there are many cases when it gives a non-zero
output when it should be 0.
I did notice one correct answer as 1 for wigner_3j(0,0,0,0,0,0)

Another problem is wigner_3j or even just wigner does not even appear in Maxima help at all !

How is one supposed to use user contributed files with extension .mac in general for example ?