2020-10-01 13:56:23 +0200 commented answer Defining 4jm Wigner symbols Perfect, thanks for your help! 2020-10-01 13:55:54 +0200 answered a question Defining 4jm Wigner symbols Perfect, thanks! 2020-10-01 13:55:31 +0200 received badge ● Supporter (source) 2020-10-01 13:55:28 +0200 received badge ● Scholar (source) 2020-09-30 23:23:55 +0200 received badge ● Nice Question (source) 2020-09-30 23:01:38 +0200 received badge ● Student (source) 2020-09-30 22:15:41 +0200 asked a question Defining 4jm Wigner symbols Hi everyone, I am a neophyte and I can't understand my error in spite of the many tutorials I have watched. I want to define the 4jm Wigner symbols, which should basically be defined as: var('m') wigner_4j(j1,j2,j3,j4,j,m1,m2,m3,m4) = sum(wigner_3j(j1,j2,j,m1,m2,m)*wigner_3j(j,j3,j4,-m,m3,m4),m,-j,j)  I get plenty of errors that I can't fix. It is weird to me because the overall logic seemed good, as it works for instance when I define in a similar manner: var('n') b(p,q) = sum(binomial(p,n)*binomial(q,n),n,0,min(p,q))  Thanks for your help!