Merge pull request #52 from JuliaReach/schillic/51

#51 - Matrix type not preserved in operations
JuliaReach · Sep 10, 2019 · 535e22b · 535e22b
2 parents 084ce18 + eac69bd
commit 535e22b
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Showing 4 changed files with 13 additions and 4 deletions.
diff --git a/docs/src/index.md b/docs/src/index.md
@@ -46,7 +46,7 @@ of $A$
 
 ```jldoctest quickstart
 julia> 2A
-2×2 Array{Interval{Float64},2}:
+2×2 IntervalMatrix{Float64,Interval{Float64},Array{Interval{Float64},2}}:
  [0, 2]    [2, 4]
  [4, 6]  [-8, -4]
 ```
@@ -78,7 +78,7 @@ $e^{At} - I$. Then, at $t = 1.0$,
 
 ```jldoctest quickstart
 julia> A + 1/2 * A^2
-2×2 Array{Interval{Float64},2}:
+2×2 IntervalMatrix{Float64,Interval{Float64},Array{Interval{Float64},2}}:
   [1, 4.5]  [-3, 2]
  [-4, 2.5]  [-1, 9]
 ```
@@ -88,7 +88,7 @@ in the previous result:
 
 ```jldoctest quickstart
 julia> quadratic_expansion(A, 1.0)
-2×2 Array{Interval{Float64},2}:
+2×2 IntervalMatrix{Float64,Interval{Float64},Array{Interval{Float64},2}}:
   [1, 4.5]  [-2, 1]
  [-3, 1.5]   [1, 7]
 ```

diff --git a/src/arithmetic.jl b/src/arithmetic.jl
@@ -20,3 +20,6 @@ import Base: +, *
 
 *(x::Interval, M::IntervalMatrix) = IntervalMatrix(x .* M.mat)
 *(M::IntervalMatrix, x::Interval) = IntervalMatrix(x .* M.mat)
+
+*(x::Number, M::IntervalMatrix) = Interval(x) * M
+*(M::IntervalMatrix, x::Number) = Interval(x) * M
diff --git a/src/exponential.jl b/src/exponential.jl
@@ -30,7 +30,7 @@ function quadratic_expansion(A::IntervalMatrix, t)
         end
     end
 
-    W = similar(A)
+    W = IntervalMatrix(similar(A.mat))
 
     @inbounds for j in 1:n
         for i in 1:n

diff --git a/test/runtests.jl b/test/runtests.jl
@@ -25,6 +25,11 @@ end
     x = 0.0..2.0
     @test x * A == A * x ==
           IntervalMatrix([0.0..2.6 0.0..6.8; -2.0..0.0 -0.2..0.2])
+    # multiply scalar and interval matrix
+    x = 1.0
+    for A2 in [x * A, A * x]
+        @test A2 == A && typeof(A2) == typeof(A)
+    end
 end
 
 @testset "Interval matrix methods" begin
@@ -39,6 +44,7 @@ end
     m = IntervalMatrix([-1.1..0.9 -4.1.. -3.9; 3.9..4.1 -1.1..0.9])
     a_over = expm_overapproximation(m, 1.0, 4)
     a_under = expm_underapproximation(m, 1.0, 4)
+    @test a_over isa IntervalMatrix && a_under isa IntervalMatrix
 end
 
 @testset "Interval matrix split" begin