From c7115c689ef7e28c2ca894647a54f7a0387a109d Mon Sep 17 00:00:00 2001
From: kalmarek <kalmar@amu.edu.pl>
Date: Tue, 14 Aug 2018 19:28:24 +0200
Subject: [PATCH] preserve storage type of X.coeffs

---
 src/GroupRings.jl | 39 ++++++++++++++++++++-------------------
 1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/src/GroupRings.jl b/src/GroupRings.jl
index b4c57ca..63187da 100644
--- a/src/GroupRings.jl
+++ b/src/GroupRings.jl
@@ -114,10 +114,17 @@ end
 #
 ###############################################################################
 
+# sparse storage:
+
 zero(RG::GroupRing, T::Type=Int) = RG(T)
 one(RG::GroupRing, T::Type=Int) = RG(RG.group(), T)
 one(RG::GroupRing{R}, T::Type=Int) where {R<:Ring} = RG(one(RG.group()), T)
 
+function (RG::GroupRing)(T::Type=Int)
+   isdefined(RG, :basis) || throw("Can not coerce without basis of GroupRing")
+   return GroupRingElem(spzeros(T,length(RG.basis)), RG)
+end
+
 function (RG::GroupRing)(i::Int, T::Type=Int)
    elt = RG(T)
    elt[RG.group()] = i
@@ -130,24 +137,12 @@ function (RG::GroupRing{R})(i::Int, T::Type=Int) where {R<:Ring}
    return elt
 end
 
-function (RG::GroupRing)(T::Type=Int)
-   isdefined(RG, :basis) || throw("Can not coerce without basis of GroupRing")
-   return GroupRingElem(spzeros(T,length(RG.basis)), RG)
-end
-
 function (RG::GroupRing)(g::GroupElem, T::Type=Int)
    result = RG(T)
    result[RG.group(g)] = one(T)
    return result
 end
 
-function (RG::GroupRing)(x::AbstractVector{T}) where {T<:Number}
-   length(x) == length(RG.basis) || throw("Can not coerce to $RG: lengths differ")
-   result = RG(T)
-   result.coeffs = x
-   return result
-end
-
 function (RG::GroupRing{Gr,T})(V::Vector{T}, S::Type=Int) where {Gr<:Group, T<:GroupElem}
    res = RG(S)
    for g in V
@@ -156,20 +151,26 @@ function (RG::GroupRing{Gr,T})(V::Vector{T}, S::Type=Int) where {Gr<:Group, T<:G
     return res
 end
 
+# keep storage type
+
+function (RG::GroupRing)(x::AbstractVector{T}) where T
+   length(x) == length(RG.basis) || throw("Can not coerce to $RG: lengths differ")
+   return GroupRingElem(x, RG)
+end
+
 function (RG::GroupRing)(X::GroupRingElem)
    RG == parent(X) || throw("Can not coerce!")
    return RG(X.coeffs)
 end
 
-function (RG::GroupRing)(X::GroupRingElem, emb::Function)
+function (RG::GroupRing)(f::Function, X::GroupRingElem)
    isdefined(RG, :basis) || throw("Can not coerce without basis of GroupRing")
-   result = RG(eltype(X.coeffs))
-   T = typeof(X.coeffs)
-   result.coeffs = T(result.coeffs)
-   for g in parent(X).basis
-      result[emb(g)] = X[g]
+   res = RG(zeros(X.coeffs))
+
+   for g in RG.basis
+      res[f(g)] = X[g]
    end
-   return result
+   return res
 end
 
 ###############################################################################