Read("FlabbyResolution.gap");

modnearzero := function(a,b)
  local c;
  c:=a mod b;
  if 2*c>b then
    c:=c-b;
  fi;
  return c;
end;

matmod := function(M,snf)
  local d,ans,i,row,j;
  d:=Length(snf);
  ans:=[];
  for i in [1..d] do
    row:=[];
    for j in [1..d] do
      if i=j and snf[i]=1 then
        Add(row,1);
      else
        Add(row,modnearzero(M[i][j],snf[j]));
      fi;
    od;
    Add(ans,row);
  od;
  return ans;
end;

MultInvFieldToNoetherProblem := function(Mgen,Pgen)
  local Qgen,snftrans,snf,act;
  Qgen:=Sum(TransformationMat(Mgen,Pgen));
  snftrans:=SmithNormalFormIntegerMatTransforms(Qgen);
  snf:=Sum(snftrans.normal);
  act:=List(Pgen,x->TransposedMat(x)^-1);
  Apply(act,x->matmod(x^snftrans.coltrans,snf));
  return rec(snf:=snf,act:=act);
end;