🧪 Add Lanczos tests

Author: matteosecli

test/core-test/correlations_and_spectrum.jl

@@ -13,10 +13,12 @@
     ω_l2 = range(0, 3, length = 1000)
     spec2 = spectrum(H, ω_l2, c_ops, a', a)
     spec3 = spectrum(H, ω_l2, c_ops, a', a; solver = PseudoInverse())
+    spec4 = spectrum(H, ω_l2, c_ops, a', a; solver = Lanczos())
 
     spec1 = spec1 ./ maximum(spec1)
     spec2 = spec2 ./ maximum(spec2)
     spec3 = spec3 ./ maximum(spec3)
+    spec4 = spec4 ./ maximum(spec4)
 
     test_func1 = maximum(real.(spec1)) * (0.1 / 2)^2 ./ ((ω_l1 .- 1) .^ 2 .+ (0.1 / 2)^2)
     test_func2 = maximum(real.(spec2)) * (0.1 / 2)^2 ./ ((ω_l2 .- 1) .^ 2 .+ (0.1 / 2)^2)
@@ -26,12 +28,14 @@
     @test sum(abs2.(spec2[idxs2] .- test_func2[idxs2])) / sum(abs2.(test_func2[idxs2])) < 0.01
     @test all(corr1 .≈ corr2)
     @test all(spec2 .≈ spec3)
+    @test all(spec2 .≈ spec4)
 
     @testset "Type Inference spectrum" begin
         @inferred correlation_2op_1t(H, nothing, t_l, c_ops, a', a; progress_bar = Val(false))
         @inferred spectrum_correlation_fft(t_l, corr1)
         @inferred spectrum(H, ω_l2, c_ops, a', a)
         @inferred spectrum(H, ω_l2, c_ops, a', a; solver = PseudoInverse())
+        @inferred spectrum(H, ω_l2, c_ops, a', a; solver = Lanczos())
     end
 
     # tlist and τlist checks