Fix: Complex SubArray times real Matrix

stdlib/LinearAlgebra/src/matmul.jl

@@ -141,12 +141,14 @@ function (*)(A::AbstractMatrix, B::AbstractMatrix)
  mul!(similar(B, TS, (size(A,1), size(B,2))), A, B)
 end
 mul!(C::StridedMatrix{T}, A::StridedVecOrMat{T}, B::StridedVecOrMat{T}) where {T<:BlasFloat} = gemm_wrapper!(C, 'N', 'N', A, B)
+# Complex Matrix times real matrix: We use that it is generally faster to reinterpret the
+# first matrix as a real matrix and carry out real matrix matrix multiply
 for elty in (Float32,Float64)
  @eval begin
  function mul!(C::StridedMatrix{Complex{$elty}}, A::StridedVecOrMat{Complex{$elty}}, B::StridedVecOrMat{$elty})
  Afl = reinterpret($elty, A)
  Cfl = reinterpret($elty, C)
- gemm_wrapper!(Cfl, 'N', 'N', Afl, B)
+ mul!(Cfl, Afl, B)
  return C
  end
  end

stdlib/LinearAlgebra/test/matmul.jl

@@ -161,6 +161,37 @@ end
  @test *(Asub, adjoint(Asub)) == *(Aref, adjoint(Aref))
 end
 
+@testset "Complex matrix x real MatOrVec etc (issue #29224)" for T1 in (Float32,Float64)
+ for T2 in (Float32,Float64)
+ for arg1_real in (true,false)
+ @testset "Combination $T1 $T2 $arg1_real $arg2_real" for arg2_real in (true,false)
+ A0 = reshape(Vector{T1}(1:25),5,5) .+
+ (arg1_real ? 0 : 1im*reshape(Vector{T1}(-3:21),5,5))
+ A = view(A0,1:2,1:2)
+ B = Matrix{T2}([1.0 3.0; -1.0 2.0]).+
+ (arg2_real ? 0 : 1im*Matrix{T2}([3.0 4; -1 10]))
+ AB_correct = copy(A)*B
+ AB = A*B; # view times matrix
+ @test AB ≈ AB_correct
+ A1 = view(A0,:,1:2) # rectangular view times matrix
+ @test A1*B ≈ copy(A1)*B
+ B1 = view(B,1:2,1:2);
+ AB1 = A*B1; # view times view
+ @test AB1 ≈ AB_correct
+ x = Vector{T2}([1.0;10.0]) .+ (arg2_real ? 0 : 1im*Vector{T2}([3;-1]))
+ Ax_exact = copy(A)*x
+ Ax = A*x # view times vector
+ @test Ax ≈ Ax_exact
+ x1 = view(x,1:2)
+ Ax1 = A*x1 # view times viewed vector
+ @test Ax1 ≈ Ax_exact
+ @test copy(A)*x1 ≈ Ax_exact # matrix times viewed vector
+ end
+ end
+ end
+end
+
+
 @testset "issue #15286" begin
  A = reshape(map(Float64, 1:20), 5, 4)
  C = zeros(8, 8)