Add tests

Author: lkdvos

test/test_tensoroperations.jl

@@ -0,0 +1,41 @@
+using Test: @test, @testset
+using TensorOperations: @tensor, ncon
+using TensorAlgebra: Matricize
+
+elts = (Float32, Float64, ComplexF32, ComplexF64)
+
+@testset "tensor network examples ($T)" for T in elts
+  D1, D2, D3 = 30, 40, 20
+  d1, d2 = 2, 3
+  A1 = rand(T, D1, d1, D2) .- 1//2
+  A2 = rand(T, D2, d2, D3) .- 1//2
+  rhoL = rand(T, D1, D1) .- 1//2
+  rhoR = rand(T, D3, D3) .- 1//2
+  H = rand(T, d1, d2, d1, d2) .- 1//2
+
+  @tensor HrA12[a, s1, s2, c] :=
+    rhoL[a, a'] * A1[a', t1, b] * A2[b, t2, c'] * rhoR[c', c] * H[s1, s2, t1, t2]
+  @tensor backend = Matricize() HrA12′[a, s1, s2, c] :=
+    rhoL[a, a'] * A1[a', t1, b] * A2[b, t2, c'] * rhoR[c', c] * H[s1, s2, t1, t2]
+
+  @test HrA12 ≈ HrA12′
+  @test HrA12 ≈ ncon(
+    [rhoL, H, A2, rhoR, A1],
+    [[-1, 1], [-2, -3, 4, 5], [2, 5, 3], [3, -4], [1, 4, 2]];
+    backend=Matricize(),
+  )
+  E = @tensor rhoL[a', a] *
+    A1[a, s, b] *
+    A2[b, s', c] *
+    rhoR[c, c'] *
+    H[t, t', s, s'] *
+    conj(A1[a', t, b']) *
+    conj(A2[b', t', c'])
+  @test E ≈ @tensor backend = Matricize() rhoL[a', a] *
+    A1[a, s, b] *
+    A2[b, s', c] *
+    rhoR[c, c'] *
+    H[t, t', s, s'] *
+    conj(A1[a', t, b']) *
+    conj(A2[b', t', c'])
+end