also check for equal orderings in map_ideal (#821)

src/map/alghom.jl

@@ -39,7 +39,21 @@ function map_ideal(f::Map(SAlgHom), I::sideal)
  f.ptr, f.codomain.ptr, libSingular.ndCopyMap())
 
  J = Ideal(f.codomain,ptr)
- J.isGB = I.isGB
+ # compare the orderings of f.domain.ptr and f.codomain.ptr
+ domain_ord=Cint[]
+ libSingular.rOrdering_helper(domain_ord, f.domain.ptr)
+ codomain_ord=Cint[]
+ libSingular.rOrdering_helper(codomain_ord, f.codomain.ptr)
+ equal_ordering=true
+ for i in 1:size(domain_ord,1)
+ if domain_ord[i] != codomain_ord[i]
+ equal_ordering=false
+ break
+ end
+ end
+ if equal_ordering
+ J.isGB = I.isGB
+ end
  return J
 end