Check tlist properties (#378)

Author: albertomercurio

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Fix Dynamical Fock Dimension states saving due to wrong saving of dimensions. ([#375])
 - Support a list of observables for `expect`. ([#374], [#376])
+- Add checks for `tlist` in time evolution solvers. The checks are to ensure that `tlist` is not empty, the elements are in increasing order, and the elements are unique. ([#378])
 
 ## [v0.25.0]
 Release date: 2025-01-20
@@ -89,3 +90,4 @@ Release date: 2024-11-13
 [#374]: https://github.com/qutip/QuantumToolbox.jl/issues/374
 [#375]: https://github.com/qutip/QuantumToolbox.jl/issues/375
 [#376]: https://github.com/qutip/QuantumToolbox.jl/issues/376
+[#378]: https://github.com/qutip/QuantumToolbox.jl/issues/378

src/time_evolution/lr_mesolve.jl

@@ -409,7 +409,7 @@ function lr_mesolveProblem(
     c_ops = get_data.(c_ops)
     e_ops = get_data.(e_ops)
 
-    t_l = convert(Vector{_FType(H)}, tlist)
+    t_l = _check_tlist(tlist, _FType(H))
 
     # Initialization of Arrays
     expvals = Array{ComplexF64}(undef, length(e_ops), length(t_l))

src/time_evolution/mcsolve.jl

@@ -167,7 +167,7 @@ function mcsolveProblem(
     c_ops isa Nothing &&
         throw(ArgumentError("The list of collapse operators must be provided. Use sesolveProblem instead."))
 
-    tlist = convert(Vector{_FType(ψ0)}, tlist) # Convert it to support GPUs and avoid type instabilities for OrdinaryDiffEq.jl
+    tlist = _check_tlist(tlist, _FType(ψ0))
 
     H_eff_evo = _mcsolve_make_Heff_QobjEvo(H, c_ops)
 

src/time_evolution/mesolve.jl

@@ -68,7 +68,7 @@ function mesolveProblem(
     haskey(kwargs, :save_idxs) &&
         throw(ArgumentError("The keyword argument \"save_idxs\" is not supported in QuantumToolbox."))
 
-    tlist = convert(Vector{_FType(ψ0)}, tlist) # Convert it to support GPUs and avoid type instabilities for OrdinaryDiffEq.jl
+    tlist = _check_tlist(tlist, _FType(ψ0))
 
     L_evo = _mesolve_make_L_QobjEvo(H, c_ops)
     check_dimensions(L_evo, ψ0)

src/time_evolution/sesolve.jl

@@ -59,7 +59,7 @@ function sesolveProblem(
     haskey(kwargs, :save_idxs) &&
         throw(ArgumentError("The keyword argument \"save_idxs\" is not supported in QuantumToolbox."))
 
-    tlist = convert(Vector{_FType(ψ0)}, tlist) # Convert it to support GPUs and avoid type instabilities for OrdinaryDiffEq.jl
+    tlist = _check_tlist(tlist, _FType(ψ0))
 
     H_evo = _sesolve_make_U_QobjEvo(H) # Multiply by -i
     isoper(H_evo) || throw(ArgumentError("The Hamiltonian must be an Operator."))

src/time_evolution/ssesolve.jl

@@ -162,7 +162,7 @@ function ssesolveProblem(
     sc_ops isa Nothing &&
         throw(ArgumentError("The list of collapse operators must be provided. Use sesolveProblem instead."))
 
-    tlist = convert(Vector{Float64}, tlist) # Convert it into Float64 to avoid type instabilities for StochasticDiffEq.jl
+    tlist = _check_tlist(tlist, _FType(ψ0))
 
     H_eff_evo = _mcsolve_make_Heff_QobjEvo(H, sc_ops)
     isoper(H_eff_evo) || throw(ArgumentError("The Hamiltonian must be an Operator."))

src/time_evolution/time_evolution.jl

@@ -212,6 +212,19 @@ struct DiscreteLindbladJumpCallback <: LindbladJumpCallbackType end
 
 ContinuousLindbladJumpCallback(; interp_points::Int = 10) = ContinuousLindbladJumpCallback(interp_points)
 
+function _check_tlist(tlist, T::Type)
+    tlist2 = convert(Vector{T}, tlist) # Convert it to support GPUs and avoid type instabilities for OrdinaryDiffEq.jl
+
+    # Check if the list of times is not empty
+    isempty(tlist2) && throw(ArgumentError("The time list must not be empty."))
+    # Check if the list of times is sorted
+    issorted(tlist2) || throw(ArgumentError("The time list must be sorted."))
+    # Check if the list of times is unique
+    allunique(tlist2) || throw(ArgumentError("The time list must be unique."))
+
+    return tlist2
+end
+
 #######################################
 
 function liouvillian_floquet(

test/core-test/time_evolution.jl

@@ -63,6 +63,13 @@
               "abstol = $(sol2.abstol)\n" *
               "reltol = $(sol2.reltol)\n"
 
+        tlist1 = Float64[]
+        tlist2 = [0, 0.2, 0.1]
+        tlist3 = [0, 0.1, 0.1, 0.2]
+        @test_throws ArgumentError sesolve(H, ψ0, tlist1, progress_bar = Val(false))
+        @test_throws ArgumentError sesolve(H, ψ0, tlist2, progress_bar = Val(false))
+        @test_throws ArgumentError sesolve(H, ψ0, tlist3, progress_bar = Val(false))
+
         @testset "Memory Allocations" begin
             allocs_tot = @allocations sesolve(H, ψ0, tlist, e_ops = e_ops, progress_bar = Val(false)) # Warm-up
             allocs_tot = @allocations sesolve(H, ψ0, tlist, e_ops = e_ops, progress_bar = Val(false))
@@ -190,6 +197,19 @@
               "abstol = $(sol_sse.abstol)\n" *
               "reltol = $(sol_sse.reltol)\n"
 
+        tlist1 = Float64[]
+        tlist2 = [0, 0.2, 0.1]
+        tlist3 = [0, 0.1, 0.1, 0.2]
+        @test_throws ArgumentError mesolve(H, ψ0, tlist1, c_ops, progress_bar = Val(false))
+        @test_throws ArgumentError mesolve(H, ψ0, tlist2, c_ops, progress_bar = Val(false))
+        @test_throws ArgumentError mesolve(H, ψ0, tlist3, c_ops, progress_bar = Val(false))
+        @test_throws ArgumentError mcsolve(H, ψ0, tlist1, c_ops, progress_bar = Val(false))
+        @test_throws ArgumentError mcsolve(H, ψ0, tlist2, c_ops, progress_bar = Val(false))
+        @test_throws ArgumentError mcsolve(H, ψ0, tlist3, c_ops, progress_bar = Val(false))
+        @test_throws ArgumentError ssesolve(H, ψ0, tlist1, c_ops, progress_bar = Val(false))
+        @test_throws ArgumentError ssesolve(H, ψ0, tlist2, c_ops, progress_bar = Val(false))
+        @test_throws ArgumentError ssesolve(H, ψ0, tlist3, c_ops, progress_bar = Val(false))
+
         # Time-Dependent Hamiltonian
         # ssesolve is slow to be run on CI. It is not removed from the test because it may be useful for testing in more powerful machines.