Fix TruncationIntersection implementation and test (#300)

* some more small truncation fixes

* add tests

Author: lkdvos

src/factorizations/truncation.jl

@@ -225,19 +225,19 @@ function MAK.findtruncated_svd(values::SectorDict, strategy::TruncationSpace)
 end
 
 function MAK.findtruncated(values::SectorDict, strategy::TruncationIntersection)
-    inds = map(Base.Fix1(MAK.findtruncated, values), strategy)
+    inds = map(Base.Fix1(MAK.findtruncated, values), strategy.components)
     return SectorDict(
         c => mapreduce(
-                Base.Fix2(getindex, c), _ind_intersect, inds;
+                Base.Fix2(getindex, c), MatrixAlgebraKit._ind_intersect, inds;
                 init = trues(length(values[c]))
             ) for c in intersect(map(keys, inds)...)
     )
 end
-function MAK.findtruncated_svd(Sd::SectorDict, strategy::TruncationIntersection)
-    inds = map(Base.Fix1(MAK.findtruncated_svd, Sd), strategy)
+function MAK.findtruncated_svd(values::SectorDict, strategy::TruncationIntersection)
+    inds = map(Base.Fix1(MAK.findtruncated_svd, values), strategy.components)
     return SectorDict(
         c => mapreduce(
-                Base.Fix2(getindex, c), _ind_intersect, inds;
+                Base.Fix2(getindex, c), MatrixAlgebraKit._ind_intersect, inds;
                 init = trues(length(values[c]))
             ) for c in intersect(map(keys, inds)...)
     )

test/factorizations.jl

@@ -260,6 +260,14 @@ for V in spacelist
                 @test isisometry(U4)
                 @test isisometry(Vᴴ4; side = :right)
                 @test norm(t - U4 * S4 * Vᴴ4) <= 0.5
+
+                trunc = truncrank(dim(domain(S)) ÷ 2) & trunctol(; atol = λ - 10eps(λ))
+                U5, S5, Vᴴ5 = @constinferred svd_trunc(t; trunc)
+                @test t * Vᴴ5' ≈ U5 * S5
+                @test isisometry(U5)
+                @test isisometry(Vᴴ5; side = :right)
+                @test minimum(minimum, values(LinearAlgebra.diag(S5))) >= λ
+                @test dim(domain(S5)) ≤ dim(domain(S)) ÷ 2
             end
         end