Add cycle_length for PermGroupElem (#4359)

oscar-system · Nov 28, 2024 · 2cba15c · 2cba15c
1 parent 39afcf9
commit 2cba15c
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diff --git a/src/GAP/wrappers.jl b/src/GAP/wrappers.jl
@@ -62,6 +62,7 @@ GAP.@wrap ConjugateSubgroup(x::GapObj, y::GapObj)::GapObj
 GAP.@wrap Core(x::GapObj, y::GapObj)::GapObj
 GAP.@wrap CycleFromList(x::GapObj)::GapObj
 GAP.@wrap CycleStructurePerm(x::GapObj)::GapObj
+GAP.@wrap CYCLE_LENGTH_PERM_INT(x::GapObj, y::Int)::Int
 GAP.@wrap CycList(x::GapObj)::GapInt
 GAP.@wrap CyclotomicPol(x::Int)::GapObj
 GAP.@wrap DecomposeTensorProduct(x::GapObj, y::GapObj, z::GapObj)::GapObj

diff --git a/src/Groups/perm.jl b/src/Groups/perm.jl
@@ -724,6 +724,27 @@ function cycles(g::PermGroupElem)
   return cycles
 end
 
+@doc raw"""
+    cycle_length(g::PermGroupElem, i::IntegerUnion)
+
+Return the length of the cycle of `i` under the action of the permutation `g`.
+
+# Examples
+```jldoctest
+julia> g = cperm(1:3, 6:7, 8:10, 11:15)
+(1,2,3)(6,7)(8,9,10)(11,12,13,14,15)
+
+julia> cycle_length(g, 1)
+3
+
+julia> cycle_length(g, 4)
+1
+```
+"""
+function cycle_length(g::PermGroupElem, i::IntegerUnion)
+  return GAPWrap.CYCLE_LENGTH_PERM_INT(GapObj(g), GapObj(i))
+end
+
 ################################################################################
 #
 #   _perm_helper

diff --git a/src/exports.jl b/src/exports.jl
@@ -449,6 +449,7 @@ export cox_variety
 export cperm
 export cross_polytope
 export cube
+export cycle_length
 export cycle_matroid
 export cycle_structure
 export cycle_structures