Add weyl_group(::Matrix{<:IntegerUnion}) convenience constructor (#…

…4536)
oscar-system · Feb 4, 2025 · e881004 · e881004
1 parent 069bd41
commit e881004
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Showing 3 changed files with 24 additions and 5 deletions.
diff --git a/src/LieTheory/RootSystem.jl b/src/LieTheory/RootSystem.jl
@@ -6,7 +6,7 @@
 
 @doc raw"""
     root_system(cartan_matrix::ZZMatrix; check::Bool=true, detect_type::Bool=true) -> RootSystem
-    root_system(cartan_matrix::Matrix{<:Integer}; check::Bool=true, detect_type::Bool=true) -> RootSystem
+    root_system(cartan_matrix::Matrix{<:IntegerUnion}; check::Bool=true, detect_type::Bool=true) -> RootSystem
 
 Construct the root system defined by the given (generalized) Cartan matrix.
 
@@ -32,7 +32,7 @@ function root_system(cartan_matrix::ZZMatrix; check::Bool=true, detect_type::Boo
   return RootSystem(cartan_matrix; check, detect_type)
 end
 
-function root_system(cartan_matrix::Matrix{<:Integer}; kwargs...)
+function root_system(cartan_matrix::Matrix{<:IntegerUnion}; kwargs...)
   return root_system(matrix(ZZ, cartan_matrix); kwargs...)
 end
 

diff --git a/src/LieTheory/WeylGroup.jl b/src/LieTheory/WeylGroup.jl
@@ -8,12 +8,19 @@
 ###############################################################################
 
 @doc raw"""
-    weyl_group(cartan_matrix::ZZMatrix) -> WeylGroup
+    weyl_group(cartan_matrix::ZZMatrix; check::Bool=true) -> WeylGroup
+    weyl_group(cartan_matrix::Matrix{<:IntegerUnion}; check::Bool=true) -> WeylGroup
 
 Construct the Weyl group defined by the given (generalized) Cartan matrix.
+
+If `check=true` the function will verify that `cartan_matrix` is indeed a generalized Cartan matrix.
 """
-function weyl_group(cartan_matrix::ZZMatrix)
-  return weyl_group(root_system(cartan_matrix))
+function weyl_group(cartan_matrix::ZZMatrix; kwargs...)
+  return weyl_group(root_system(cartan_matrix; kwargs...))
+end
+
+function weyl_group(cartan_matrix::Matrix{<:IntegerUnion}; kwargs...)
+  return weyl_group(root_system(cartan_matrix; kwargs...))
 end
 
 @doc raw"""

diff --git a/test/LieTheory/WeylGroup.jl b/test/LieTheory/WeylGroup.jl
@@ -4,6 +4,18 @@
   end
 
   @testset "constructors" begin
+    @testset "weyl_group(::Matrix{<:IntegerUnion})" begin
+      W = weyl_group([2 -1; -1 2]) # Matrix{Int}
+      @test ngens(W) == 2
+      @test order(W) == 6
+      @test isfinite(W) == true
+
+      W = weyl_group(ZZ.([2 -1; -1 2])) # Matrix{ZZRingElem}
+      @test ngens(W) == 2
+      @test order(W) == 6
+      @test isfinite(W) == true
+    end
+
     @testset "weyl_group(::ZZMatrix)" begin
       W = weyl_group(cartan_matrix(:A, 2))
       @test isfinite(W) == true