rootsof problem -- design doesn't have enough info!



rootsof(x^3+5)  represents the set of 3  cube roots of -5.

what does

rootsof(x^3+y^4) represent?    3  cube roots of y^4 or   4 4th roots of x^3?

Mathematica handles this situation by requiring that the argument to 
Root or RootSum that represents a polynomial be a function.

In the ambiguous case above,  #^3+y^4&  is one choice, which would 
correspond to Maxima's

   lambda([x],x^3+y^4).

Similarly for the other case, x^3+#^4&.  
Mathematica syntax  f[#]&  is essentially  lambda([%1], f(%1)) in Maxima.

Who added integrate_use_rootsof  etc?  The essential idea is OK in 
there, but is problematical.
RJF