Handle empty matrices in svd_full and add tests (#37)

* Special case svd_full on empty matrices

* Also add tests

* Bump v0.2.4

Author: lkdvos

Project.toml

@@ -1,7 +1,7 @@
 name = "MatrixAlgebraKit"
 uuid = "6c742aac-3347-4629-af66-fc926824e5e4"
 authors = ["Jutho <jutho.haegeman@ugent.be> and contributors"]
-version = "0.2.3"
+version = "0.2.4"
 
 [deps]
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"

src/implementations/svd.jl

@@ -74,6 +74,12 @@ function svd_full!(A::AbstractMatrix, USVᴴ, alg::LAPACK_SVDAlgorithm)
     fill!(S, zero(eltype(S)))
     m, n = size(A)
     minmn = min(m, n)
+    if minmn == 0
+        one!(U)
+        zero!(S)
+        one!(Vᴴ)
+        return USVᴴ
+    end
     if alg isa LAPACK_QRIteration
         isempty(alg.kwargs) ||
             throw(ArgumentError("LAPACK_QRIteration does not accept any keyword arguments"))

test/svd.jl

@@ -8,7 +8,7 @@ using MatrixAlgebraKit: TruncatedAlgorithm, TruncationKeepAbove, diagview
 @testset "svd_compact! for T = $T" for T in (Float32, Float64, ComplexF32, ComplexF64)
     rng = StableRNG(123)
     m = 54
-    @testset "size ($m, $n)" for n in (37, m, 63)
+    @testset "size ($m, $n)" for n in (37, m, 63, 0)
         k = min(m, n)
         if LinearAlgebra.LAPACK.version() < v"3.12.0"
             algs = (LAPACK_DivideAndConquer(), LAPACK_QRIteration(), LAPACK_Bisection(),
@@ -57,7 +57,7 @@ end
 @testset "svd_full! for T = $T" for T in (Float32, Float64, ComplexF32, ComplexF64)
     rng = StableRNG(123)
     m = 54
-    @testset "size ($m, $n)" for n in (37, m, 63)
+    @testset "size ($m, $n)" for n in (37, m, 63, 0)
         @testset "algorithm $alg" for alg in
                                       (LAPACK_DivideAndConquer(), LAPACK_QRIteration())
             A = randn(rng, T, m, n)