eval -- evaluate the dual of a root at something

Ways to use eval :

• eval(RootSystem,Weight,Root) -- evaluate the dual of a root at a Weight
• eval(RootSystem,Weight,ZZ) -- evaluate the dual of a simple root at a Weight
• eval(RootSystem,ZZ,Root) -- evaluate the dual of a root at a fundamental weight
• eval(RootSystem,ZZ,ZZ) -- evaluate the dual of a simple root at another one

For the programmer

The object eval is a method function.