symmetry check in setindex! for Symmetric/Hermitian

Author: jishnub

src/symmetric.jl

@@ -229,6 +229,12 @@ const SelfAdjoint = Union{Symmetric{<:Real}, Hermitian{<:Number}}
 wrappertype(::Union{Symmetric, SymTridiagonal}) = Symmetric
 wrappertype(::Hermitian) = Hermitian
 
+_symherm_wrapperop(::Symmetric) = symmetric
+_symherm_wrapperop(::Hermitian) = hermitian
+
+_conjugation(::Symmetric) = transpose
+_conjugation(::Hermitian) = adjoint
+
 size(A::HermOrSym) = size(A.data)
 axes(A::HermOrSym) = axes(A.data)
 @inline function Base.isassigned(A::HermOrSym, i::Int, j::Int)
@@ -266,6 +272,7 @@ Base._reverse(A::Symmetric, ::Colon) = Symmetric(reverse(A.data), A.uplo == 'U'
 
 @propagate_inbounds function setindex!(A::Symmetric, v, i::Integer, j::Integer)
     i == j || throw(ArgumentError("Cannot set a non-diagonal index in a symmetric matrix"))
+    issymmetric(v) || throw(ArgumentError("cannot set a diagonal element of a symmetric matrix to an asymmetric value"))
     setindex!(A.data, v, i, j)
     return A
 end
@@ -276,8 +283,8 @@ Base._reverse(A::Hermitian, ::Colon) = Hermitian(reverse(A.data), A.uplo == 'U'
 @propagate_inbounds function setindex!(A::Hermitian, v, i::Integer, j::Integer)
     if i != j
         throw(ArgumentError("Cannot set a non-diagonal index in a Hermitian matrix"))
-    elseif !isreal(v)
-        throw(ArgumentError("Cannot set a diagonal entry in a Hermitian matrix to a nonreal value"))
+    elseif !ishermitian(v)
+        throw(ArgumentError("cannot set a diagonal element of a hermitian matrix to a non-hermitian value"))
     else
         setindex!(A.data, v, i, j)
     end
@@ -288,9 +295,6 @@ Base.dataids(A::HermOrSym) = Base.dataids(parent(A))
 Base.unaliascopy(A::Hermitian) = Hermitian(Base.unaliascopy(parent(A)), sym_uplo(A.uplo))
 Base.unaliascopy(A::Symmetric) = Symmetric(Base.unaliascopy(parent(A)), sym_uplo(A.uplo))
 
-_conjugation(::Symmetric) = transpose
-_conjugation(::Hermitian) = adjoint
-
 diag(A::Symmetric) = symmetric.(diag(parent(A)), sym_uplo(A.uplo))
 diag(A::Hermitian) = hermitian.(diag(parent(A)), sym_uplo(A.uplo))
 

test/symmetric.jl

@@ -1180,4 +1180,15 @@ end
     end
 end
 
+@testset "block-symmetric setindex!" begin
+    A = fill([1 2; 3 4], 2, 2)
+    v = [1 2; 3 4]
+    H = Hermitian(A)
+    h_msg = "cannot set a diagonal element of a hermitian matrix to a non-hermitian value"
+    @test_throws h_msg H[1,1] = v
+    S = Symmetric(A)
+    s_msg = "cannot set a diagonal element of a symmetric matrix to an asymmetric value"
+    @test_throws s_msg S[1,1] = v
+end
+
 end # module TestSymmetric