Merge pull request #366 from Ickaser/nan_interp

Make extrapolation with NaN Unitful-friendly

Project.toml

@@ -41,6 +41,7 @@ SafeTestsets = "0.1"
 StableRNGs = "1"
 Symbolics = "5.29, 6"
 Test = "1"
+Unitful = "1"
 Zygote = "0.6.70"
 julia = "1.10"
 
@@ -57,7 +58,8 @@ SafeTestsets = "1bc83da4-3b8d-516f-aca4-4fe02f6d838f"
 StableRNGs = "860ef19b-820b-49d6-a774-d7a799459cd3"
 Symbolics = "0c5d862f-8b57-4792-8d23-62f2024744c7"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
 Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"
 
 [targets]
-test = ["Aqua", "BenchmarkTools", "SafeTestsets", "ChainRulesCore", "Optim", "RegularizationTools", "Test", "StableRNGs", "FiniteDifferences", "QuadGK", "ForwardDiff", "Symbolics", "Zygote"]
+test = ["Aqua", "BenchmarkTools", "SafeTestsets", "ChainRulesCore", "Optim", "RegularizationTools", "Test", "StableRNGs", "FiniteDifferences", "QuadGK", "ForwardDiff", "Symbolics", "Unitful", "Zygote"]

src/interpolation_methods.jl

@@ -9,9 +9,9 @@ function _interpolate(A::LinearInterpolation{<:AbstractVector}, t::Number, igues
     if isnan(t)
         # For correct derivative with NaN
         idx = firstindex(A.u)
-        t1 = t2 = one(eltype(A.t))
-        u1 = u2 = one(eltype(A.u))
-        slope = t * get_parameters(A, idx)
+        t1 = t2 = oneunit(eltype(A.t))
+        u1 = u2 = oneunit(eltype(A.u))
+        slope = t/t * get_parameters(A, idx)
     else
         idx = get_idx(A, t, iguess)
         t1, t2 = A.t[idx], A.t[idx + 1]

test/interpolation_tests.jl

@@ -3,6 +3,7 @@ using FindFirstFunctions: searchsortedfirstcorrelated
 using StableRNGs
 using Optim, ForwardDiff
 using BenchmarkTools
+using Unitful
 
 function test_interpolation_type(T)
     @test T <: DataInterpolations.AbstractInterpolation
@@ -105,6 +106,14 @@ end
     @test isnan(A(3.5))
     @test isnan(A(4.0))
 
+    u = [0.0, 1.0, 2.0, NaN]
+    A = LinearInterpolation(u, t; extrapolate = true)
+    @test A(1.0) == 0.0
+    @test A(2.0) == 1.0
+    @test A(3.0) == 2.0
+    @test isnan(A(3.5))
+    @test isnan(A(4.0))
+
     # Test type stability
     u = Float32.(1:5)
     t = Float32.(1:5)
@@ -134,6 +143,12 @@ end
         @test @inferred(A(R64)) === A(R64)
     end
 
+    # NaN time value for Unitful arrays: issue #365
+    t = (0:3)u"s" # Unitful quantities  
+    u = [0, -2, -1, -2]u"m"  
+    A = LinearInterpolation(u, t; extrapolate = true)
+    @test isnan(A(NaN*u"s"))
+
     # Nan time value:
     t = 0.0:3  # Floats
     u = [0, -2, -1, -2]