Questions on operations on factorizations

[hermann@stamm-wilbrandt.de]

Recently I learned from Karim Belabas how to do divison of 
factorizations efficiently using matreduce(matconcat(...)):
https://pari.math.u-bordeaux.fr/archives/pari-users-2602/msg00024.html


I did not find inverse function for factorint() in doc, is there one?
This function does the job, but I would prefer to use builtin and 
documented function if available:
factval(F)=vecprod([v[1]^v[2]|v<-F~]);


I am working with factorizations a lot lately. Given factorizations f of 
x and g of y, factorization of x*y can be determined from f and g by 
factorint(factval(f),factval(g)), but for big numbers factorint() 
becomes slow. An efficient solution is:
factmul(f1,f2)=matreduce(matconcat([f1,f2]~));



Above are several functions on factorizations (divison, inverse of 
factorint, multiplication), there might be more that are useful to avoid 
factorint overhead. Are some of those available in GP already?


Regards,

Hermann.


P.S:
The efficiency of gp is amazing, searching for Carmichael numbers of 
form N=2^a*3^b+1 up to 10^70 is possible thanks to efficient 
isprime+divisors+...:
https://gist.github.com/Hermann-SW/7615a6e6121d5f743bf7a4086ccc5672