Move root system iso to its own function

oscar-system · Oct 22, 2024 · 68cdc5d · 68cdc5d
1 parent 241ac1f
commit 68cdc5d
Showing 1 changed file with 38 additions and 28 deletions.
diff --git a/experimental/LieAlgebras/src/iso_oscar_gap.jl b/experimental/LieAlgebras/src/iso_oscar_gap.jl
@@ -22,7 +22,7 @@ function _iso_oscar_gap_lie_algebra_functions(
   return (f, finv)
 end
 
-function _iso_oscar_gap(LO::LinearLieAlgebra)
+function _iso_oscar_gap(LO::LinearLieAlgebra; set_attributes::Bool=true)
   coeffs_iso = Oscar.iso_oscar_gap(coefficient_ring(LO))
   LG = GAP.Globals.LieAlgebra(
     codomain(coeffs_iso),
@@ -32,6 +32,12 @@ function _iso_oscar_gap(LO::LinearLieAlgebra)
 
   f, finv = _iso_oscar_gap_lie_algebra_functions(LO, LG, coeffs_iso)
 
+  if set_attributes && has_root_system(LO)
+    # we need to construct the root system in GAP as otherwise it may detect a different order of simple roots
+    RO = root_system(LO)
+    _iso_oscar_gap_set_root_system(LG, RO)
+  end
+
   return MapFromFunc(LO, LG, f, finv)
 end
 
@@ -59,34 +65,38 @@ function _iso_oscar_gap(LO::AbstractLieAlgebra; set_attributes::Bool=true)
   if set_attributes && has_root_system(LO)
     # we need to construct the root system in GAP as otherwise it may detect a different order of simple roots
     RO = root_system(LO)
-    RG = GAP.Globals.Objectify(
-      GAP.Globals.NewType(
-        GAP.Globals.NewFamily(GAP.Obj("RootSystemFam"), GAP.Globals.IsObject),
-        GAP.evalstr("IsAttributeStoringRep and IsRootSystemFromLieAlgebra")),
-      GAP.GapObj(Dict{Symbol,Any}()))
-    GAP.Globals.SetUnderlyingLieAlgebra(RG, LG)
-
-    cartan_trO = transpose(cartan_matrix(RO))
-    transform_root(r::RootSpaceElem) = GAP.Obj(coefficients(r) * cartan_trO)[1]
-    GAP.Globals.SetPositiveRoots(RG, GAP.Obj(transform_root.(positive_roots(RO))))
-    GAP.Globals.SetNegativeRoots(RG, GAP.Obj(transform_root.(negative_roots(RO))))
-    GAP.Globals.SetSimpleSystem(RG, GAP.Obj(transform_root.(simple_roots(RO))))
-    can_basisG = GAP.Globals.CanonicalBasis(LG)
-    pos_root_vectorsG = can_basisG[1:n_positive_roots(RO)]
-    neg_root_vectorsG = can_basisG[(n_positive_roots(RO) + 1):(2 * n_positive_roots(RO))]
-    csa_basisG = can_basisG[(2 * n_positive_roots(RO) + 1):end]
-    GAP.Globals.SetPositiveRootVectors(RG, pos_root_vectorsG)
-    GAP.Globals.SetNegativeRootVectors(RG, neg_root_vectorsG)
-    GAP.Globals.SetCanonicalGenerators(
-      RG, GAP.Obj([pos_root_vectorsG, neg_root_vectorsG, csa_basisG])
-    )
-    GAP.Globals.SetChevalleyBasis(
-      LG, GAP.Obj([pos_root_vectorsG, neg_root_vectorsG, csa_basisG])
-    )
-
-    GAP.Globals.SetCartanMatrix(RG, GAP.Obj(cartan_trO))
-    GAP.Globals.SetRootSystem(LG, RG)
+    _iso_oscar_gap_set_root_system(LG, RO)
   end
 
   return MapFromFunc(LO, LG, f, finv)
 end
+
+function _iso_oscar_gap_set_root_system(LG::GapObj, RO::RootSystem)
+  RG = GAP.Globals.Objectify(
+    GAP.Globals.NewType(
+      GAP.Globals.NewFamily(GAP.Obj("RootSystemFam"), GAP.Globals.IsObject),
+      GAP.evalstr("IsAttributeStoringRep and IsRootSystemFromLieAlgebra")),
+    GAP.GapObj(Dict{Symbol,Any}()))
+  GAP.Globals.SetUnderlyingLieAlgebra(RG, LG)
+
+  cartan_trO = transpose(cartan_matrix(RO))
+  transform_root(r::RootSpaceElem) = GAP.Obj(coefficients(r) * cartan_trO)[1]
+  GAP.Globals.SetPositiveRoots(RG, GAP.Obj(transform_root.(positive_roots(RO))))
+  GAP.Globals.SetNegativeRoots(RG, GAP.Obj(transform_root.(negative_roots(RO))))
+  GAP.Globals.SetSimpleSystem(RG, GAP.Obj(transform_root.(simple_roots(RO))))
+  can_basisG = GAP.Globals.CanonicalBasis(LG)
+  pos_root_vectorsG = can_basisG[1:n_positive_roots(RO)]
+  neg_root_vectorsG = can_basisG[(n_positive_roots(RO) + 1):(2 * n_positive_roots(RO))]
+  csa_basisG = can_basisG[(2 * n_positive_roots(RO) + 1):end]
+  GAP.Globals.SetPositiveRootVectors(RG, pos_root_vectorsG)
+  GAP.Globals.SetNegativeRootVectors(RG, neg_root_vectorsG)
+  GAP.Globals.SetCanonicalGenerators(
+    RG, GAP.Obj([pos_root_vectorsG, neg_root_vectorsG, csa_basisG])
+  )
+  GAP.Globals.SetChevalleyBasis(
+    LG, GAP.Obj([pos_root_vectorsG, neg_root_vectorsG, csa_basisG])
+  )
+
+  GAP.Globals.SetCartanMatrix(RG, GAP.Obj(cartan_trO))
+  GAP.Globals.SetRootSystem(LG, RG)
+end