fix promotion of diagonal integer matrix to non-integer power (#23510)

JuliaLang · Aug 30, 2017 · a969c2a · a969c2a · nanosoldier · Aug 31, 2017
1 parent 9c6e496
commit a969c2a
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diff --git a/base/linalg/dense.jl b/base/linalg/dense.jl
@@ -405,7 +405,8 @@ function (^)(A::AbstractMatrix{T}, p::Real) where T
 
     # Quicker return if A is diagonal
     if isdiag(A)
-        retmat = copy(A)
+        TT = promote_op(^, T, typeof(p))
+        retmat = copy_oftype(A, TT)
         for i in 1:n
             retmat[i, i] = retmat[i, i] ^ p
         end

diff --git a/test/linalg/dense.jl b/test/linalg/dense.jl
@@ -581,6 +581,11 @@ end
     end
 end
 
+@testset "diagonal integer matrix to real power" begin
+    A = Matrix(Diagonal([1, 2, 3]))
+    @test A^2.3 ≈ float(A)^2.3
+end
+
 @testset "issue #23366 (Int Matrix to Int power)" begin
     @testset "Tests for $elty" for elty in (Int128, Int16, Int32, Int64, Int8,
                                             UInt128, UInt16, UInt32, UInt64, UInt8,