I have a problem with the command. In order to learn the use of this command for Feynman Diagrams, I loaded the help page [Physics,FeynmanDiagrams], I tried the given example by accurately applying the indicated commands, i.e.
after setting Physics[Setup](mathematicalnotation = true);
"Coordinates(X, Y, Z)", next the Langrangian example "L := lambda*phi(X)^4+sigma*eta(X)^3", then the command
The error maessage is :
"Error, unexpected result from Typesetting" ,and also "
"Error, unexpected result from Typesetting".
Note these errors appear also in the help page itself.
When I click on the link included in the error message, I go on a web page indicating "There is no help page available for this error", and they recommend to discuss my problem with Maple experts on MaplePrimes.
I sew that _NP represent the normal product of fields.
Could you say me, please, where is the error ?