finegrain homespace permutation and selection

Author: Jutho

src/spaces/homspace.jl

@@ -132,6 +132,16 @@ function permute(W::HomSpace{S}, (p₁, p₂)::Index2Tuple{N₁,N₂}) where {S,
     p = (p₁..., p₂...)
     TupleTools.isperm(p) && length(p) == numind(W) ||
         throw(ArgumentError("$((p₁, p₂)) is not a valid permutation for $(W)"))
+    return select(W, (p₁, p₂))
+end
+
+"""
+    select(W::HomSpace, (p₁, p₂)::Index2Tuple{N₁,N₂})
+
+Return the `HomSpace` obtained by a selection from the domain and codomain of `W` according
+to the indices in `p₁` and `p₂` respectively.
+"""
+function select(W::HomSpace{S}, (p₁, p₂)::Index2Tuple{N₁,N₂}) where {S,N₁,N₂}
     cod = ProductSpace{S,N₁}(map(n -> W[n], p₁))
     dom = ProductSpace{S,N₂}(map(n -> dual(W[n]), p₂))
     return cod ← dom

src/tensors/diagtensor.jl

@@ -276,4 +276,4 @@ for f in
     (:exp, :cos, :sin, :tan, :cot, :cosh, :sinh, :tanh, :coth, :atan, :acot, :asinh, :sqrt,
      :log, :asin, :acos, :acosh, :atanh, :acoth)
     @eval Base.$f(d::DiagonalTensorMap) = DiagonalTensorMap($f.(d.data), d.domain)
-end
+end

src/tensors/tensoroperations.jl

@@ -59,7 +59,8 @@ end
 function TO.tensoradd_structure(A::AbstractTensorMap, pA::Index2Tuple{N₁,N₂},
                                 conjA::Bool) where {N₁,N₂}
     if !conjA
-        return permute(space(A), pA)
+        # don't use `permute` as this is also used when indices are traced
+        return select(space(A), pA)
     else
         return TO.tensoradd_structure(adjoint(A), adjointtensorindices(A, pA), false)
     end
@@ -172,7 +173,7 @@ function trace_permute!(tdst::AbstractTensorMap,
     N₁, N₂ = length(p₁), length(p₂)
 
     @boundscheck begin
-        space(tdst) == permute(space(tsrc), (p₁, p₂)) ||
+        space(tdst) == select(space(tsrc), (p₁, p₂)) ||
             throw(SpaceMismatch("trace: tsrc = $(codomain(tsrc))←$(domain(tsrc)),
                     tdst = $(codomain(tdst))←$(domain(tdst)), p₁ = $(p₁), p₂ = $(p₂)"))
         all(i -> space(tsrc, q₁[i]) == dual(space(tsrc, q₂[i])), 1:N₃) ||

test/diagtensors.jl

@@ -122,4 +122,4 @@ diagspacelist = ((ℂ^4)', ℂ[Z2Irrep](0 => 2, 1 => 3),
         @test t1 * u' ≈ TensorMap(t1) * u'
         @test t1 \ u' ≈ TensorMap(t1) \ u'
     end
-end
+end