add utility fullrank for spaces

Author: lkdvos

src/states/abstractmps.jl

@@ -93,10 +93,11 @@ Determine whether the given tensor is full rank, i.e. whether both the map from
 virtual space and the physical space to the right virtual space, and the map from the right
 virtual space and the physical space to the left virtual space are injective.
 """
-function isfullrank(A::GenericMPSTensor; side = :both)
-    Vₗ = _firstspace(A)
-    Vᵣ = _lastspace(A)
-    P = ⊗(space.(Ref(A), 2:(numind(A) - 1))...)
+isfullrank(A::GenericMPSTensor; kwargs...) = isfullrank(space(A); kwargs...)
+function isfullrank(V::TensorKit.TensorMapSpace; side = :both)
+    Vₗ = V[1]
+    Vᵣ = V[numind(V)]
+    P = ⊗(getindex.(Ref(V), 2:(numind(V) - 1))...)
     return if side === :both
         Vₗ ⊗ P ≿ Vᵣ' && Vₗ' ≾ P ⊗ Vᵣ
     elseif side === :right
@@ -129,6 +130,29 @@ function makefullrank!(A::PeriodicVector{<:GenericMPSTensor}; alg = Defaults.alg
     return A
 end
 
+function makefullrank!(virtualspaces::PeriodicVector{S}, physicalspaces::PeriodicVector{S}) where {S <: ElementarySpace}
+    haschanged = true
+    while haschanged
+        haschanged = false
+        for i in 1:length(virtualspaces)
+            Vmax = fuse(physicalspaces[i - 1], virtualspaces[i - 1])
+            if !(virtualspaces[i] ≾ Vmax)
+                virtualspaces[i] = infimum(virtualspaces[i], Vmax)
+                haschanged = true
+            end
+        end
+        for i in reverse(1:length(virtualspaces))
+            Vmax = fuse(dual(physicalspaces[i]), virtualspaces[i])
+            if !(virtualspaces[i - 1] ≾ Vmax)
+                virtualspaces[i - 1] = infimum(virtualspaces[i - 1], Vmax)
+                haschanged = true
+            end
+        end
+    end
+
+    return virtualspaces
+end
+
 # Tensor accessors
 # ----------------
 @doc """