Merge pull request #3531 from JuliaReach/schillic/oa_sspz

Fix `overapproximate` of `SSPZ` with `Zonotope` and `dom`
JuliaReach · Jun 26, 2024 · 9c07605 · 9c07605
2 parents 24d4f40 + 2c11d81
commit 9c07605
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Showing 3 changed files with 15 additions and 4 deletions.
diff --git a/src/Approximations/overapproximate_zonotope.jl b/src/Approximations/overapproximate_zonotope.jl
@@ -213,8 +213,9 @@ function _overapproximate_union_zonotope_GGP09(X::LazySet{N}) where {N}
 end
 
 # Given center, (dependent) generator matrix and exponent matrix of a (simple)
-# sparse polynomial zonotope, compute thew new center and generator matrix of
-# its zonotope overapproximation.
+# sparse polynomial zonotope, compute the new center and generator matrix of
+# its zonotope overapproximation. This method assumes that the parameter domain
+# is [-1, 1]ᵖ.
 function _zonotope_overapprox!(c, G, E)
     @inbounds for (j, g) in enumerate(eachcol(G))
         if all(iseven, E[:, j])
@@ -284,7 +285,7 @@ function overapproximate(P::SimpleSparsePolynomialZonotope, ::Type{<:Zonotope},
         end
         m, r = IA.midpoint_radius(α)
         cnew .+= m * g
-        Gnew[:, j] .= abs.(g) * r
+        Gnew[:, j] .= r * g
     end
     return Zonotope(cnew, Gnew)
 end

diff --git a/test/Sets/SimpleSparsePolynomialZonotope.jl b/test/Sets/SimpleSparsePolynomialZonotope.jl
@@ -15,7 +15,9 @@ for N in [Float64, Float32, Rational{Int}]
     @test nparams(S) == 2
     @test order(S) == 1 // 1
 
-    @test overapproximate(S, Zonotope) == Zonotope(N[3.0, 1], N[1 1; 2 1.0])
+    Z = Zonotope(N[3.0, 1], N[1 1; 2 1.0])
+    @test overapproximate(S, Zonotope) == Z
+    @test overapproximate(S, UnionSetArray{Zonotope}; nsdiv=1) == UnionSetArray([Z])
     @test length(overapproximate(S, UnionSetArray{Zonotope}; nsdiv=3)) == 9
     if vIA >= v"0.19.0"  # `mince` with non-uniform partition was introduced in IA v0.19.0
         @test length(overapproximate(S, UnionSetArray{Zonotope}; partition=(2, 3))) == 6

diff --git a/test/Sets/SparsePolynomialZonotope.jl b/test/Sets/SparsePolynomialZonotope.jl
@@ -62,6 +62,10 @@ for N in [Float64, Float32, Rational{Int}]
                            0 0 0 1 0 1;
                            0 0 0 0 1 3]
     Z = overapproximate(PZ2, Zonotope)
+    SSPZ2 = convert(SimpleSparsePolynomialZonotope, PZ2)
+    dom2 = IntervalBox(IA.interval(N(-1), N(1)), IA.interval(N(-1), N(1)))
+    Z2 = overapproximate(SSPZ2, Zonotope, dom2)
+    @test isequivalent(Z, Z2)
     CPPZ = cartesian_product(PZ, Z)
     @test center(CPPZ) == N[4, 4, 0, 0]
     @test genmat_dep(CPPZ) == N[2 1 2;
@@ -130,6 +134,10 @@ for N in [Float64, Float32, Rational{Int}]
     l2, u2 = extrema(PZ; algorithm="lowhigh")
     H2 = Hyperrectangle(; low=l2, high=u2)
     @test H2 ⊆ H1 == Hyperrectangle(N[0, 0], N[7 // 2, 5 // 2])
+    Z = Zonotope(N[0, 0], N[3//2 1 1; 3//2 0 -1])
+    @test isequivalent(overapproximate(PZ, Zonotope), Z)
+    SSPZ2 = convert(SimpleSparsePolynomialZonotope, PZ)
+    @test isequivalent(overapproximate(SSPZ2, Zonotope, dom2), Z)
 end
 
 for N in [Float64]