Merge pull request #1071 from JuliaReach/mforets/1068

#1068 - linear map of a LinearMap
JuliaReach · Jan 25, 2019 · 8f09755 · 8f09755
2 parents efe33e5 + c39f096
commit 8f09755
Show file tree

Hide file tree

Showing 3 changed files with 26 additions and 0 deletions.
diff --git a/docs/src/lib/operations.md b/docs/src/lib/operations.md
@@ -232,6 +232,7 @@ isbounded(::LinearMap)
 isempty(::LinearMap)
 vertices_list(::LinearMap{N}) where {N<:Real}
 constraints_list(::LinearMap{N}) where {N<:Real}
+linear_map(::AbstractMatrix{N}, ::LinearMap{N}) where {N}
 intersection(::LinearMap{N}, ::LazySet{N}) where {N}
 ```
 Inherited from [`LazySet`](@ref):

diff --git a/src/LinearMap.jl b/src/LinearMap.jl
@@ -376,3 +376,21 @@ We fall back to a concrete set representation and apply `linear_map`.
 function constraints_list(lm::LinearMap{N}) where {N<:Real}
     return constraints_list(linear_map(lm.M, lm.X))
 end
+
+"""
+    linear_map(M::AbstractMatrix{N}, lm::LinearMap{N}) where {N}
+
+Return the linear map of a lazy linear map.
+
+### Input
+
+- `M`  -- matrix
+- `lm` -- linear map
+
+### Output
+
+The polytope representing the linear map of the lazy linear map of a set.  
+"""
+function linear_map(M::AbstractMatrix{N}, lm::LinearMap{N}) where {N}
+     return linear_map(M * lm.M, lm.X)
+end
diff --git a/test/unit_LinearMap.jl b/test/unit_LinearMap.jl
@@ -102,6 +102,13 @@ for N in [Float64, Rational{Int}, Float32]
             @test ρ(d, lm2) ≈ ρ(d, p2)
         end
     end
+
+    # concrete linear map of a LinearMap
+    b = BallInf(N[0, 0], N(1))
+    M = N[2 3; 1 2]
+    L = LinearMap(M, b)
+    V = linear_map(M, LinearMap(M, b))
+    @test M * M * an_element(b) ∈ V
 end
 
 # tests that only work with Float64