fixed subtract bug

nmayhall-vt · Oct 25, 2023 · 211b79d · 211b79d
1 parent 68d59b8
commit 211b79d
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Showing 2 changed files with 21 additions and 1 deletion.
diff --git a/src/type_PauliSum.jl b/src/type_PauliSum.jl
@@ -60,7 +60,12 @@ end
 Subtract two `PauliSum`s. 
 """
 function Base.:-(ps1::PauliSum{N}, ps2::PauliSum{N}) where {N}
-    return PauliSum{N}(mergewith(-, ps1.ops, ps2.ops))
+    # out = PauliSum{N}()
+    # merge!(out, ps2)
+    out = deepcopy(ps2)
+    map!(x->-x, values(out.ops))
+    mergewith!(+, out.ops, ps1.ops)
+    return out 
 end
 
 Base.length(ps::PauliSum) = length(ps.ops)

diff --git a/test/tests.jl b/test/tests.jl
@@ -270,6 +270,7 @@ using Random
     for i in 1:100
         sum!(H, random_ScaledPauli(N))
     end
+
     test = true
     for (op,coeff) in diag(H).ops
         test = test && is_diagonal(op)
@@ -313,4 +314,18 @@ using Random
         # @show norm(Matrix(o)*Vector(v) - Vector(o*v)) 
         @test norm(Matrix(o)*Vector(v) - Vector(o*v)) < 1e-13 
     end
+
+
+    ##      sum/Subtract 
+    N = 8
+    H1 = PauliSum(N)
+    H2 = PauliSum(N)
+    for i in 1:100
+        sum!(H1, random_ScaledPauli(N))
+        sum!(H2, random_ScaledPauli(N))
+    end
+    @test norm(Matrix(H1) + Matrix(H2) - Matrix(H1 + H2)) < 1e-8
+    @test norm(Matrix(H1) - Matrix(H2) - Matrix(H1 - H2)) < 1e-8
 end
+
+