tests for sqrtm

Author: marius311

src/sqrtm.jl

@@ -1,10 +1,15 @@
 @inline sqrtm(A::StaticMatrix) = _sqrtm(Size(A),A)
 
-@inline function _sqrtm(::Size{(2,2)}, A::StaticMatrix)
+@inline function _sqrtm(::Size{(1,1)}, A::SA) where {SA<:StaticArray}
+    s = sqrt(A[1,1])
+    similar_type(SA,typeof(s))(s)
+end
+
+@inline function _sqrtm(::Size{(2,2)}, A::SA) where {SA<:StaticArray}
     a,b,c,d = A
     s = sqrtm(a*d-b*c)
     t = inv(sqrtm(a+d+2s))
-    similar_type(typeof(A),typeof(t))(t*(a+s), t*b, t*c, t*(d+s))
+    similar_type(SA,typeof(t))(t*(a+s), t*b, t*c, t*(d+s))
 end
 
 @inline _sqrtm(s::Size, A::StaticArray) = s(Base.sqrtm(Array(A)))

test/runtests.jl

@@ -27,6 +27,7 @@ using Base.Test
     include("solve.jl") # Strange inference / world-age error
     include("eigen.jl")
     include("expm.jl")
+    include("sqrtm.jl")
     include("chol.jl")
     include("deque.jl")
     include("io.jl")

test/sqrtm.jl

@@ -0,0 +1,7 @@
+@testset "Matrix square root" begin
+    @test sqrtm(@SMatrix [2])::SMatrix ≈ SMatrix{1,1}(sqrtm(2))
+    @test sqrtm(@SMatrix [5 2; -2 1])::SMatrix ≈ sqrtm([5 2; -2 1])
+    @test sqrtm(@SMatrix [4 2; -2 1])::SMatrix ≈ sqrtm([4 2; -2 1])
+    @test sqrtm(@SMatrix [4 2; 2 1])::SMatrix ≈ sqrtm([4 2; 2 1])
+    @test sqrtm(@SMatrix [1 2 0; 2 1 0; 0 0 1])::SizedArray{Tuple{3,3}} ≈ sqrtm([1 2 0; 2 1 0; 0 0 1])
+end