Deprecate implicit pseudo-inverses of vectors

stdlib/LinearAlgebra/src/deprecated.jl

@@ -5,3 +5,7 @@ rank(A::AbstractMatrix, tol::Real) = rank(A,rtol=tol)
 nullspace(A::AbstractVector, tol::Real) = nullspace(reshape(A, length(A), 1), rtol= tol)
 nullspace(A::AbstractMatrix, tol::Real) = nullspace(A, rtol=tol)
 pinv(A::AbstractMatrix{T}, tol::Real) where T = pinv(A, rtol=tol)
+
+# To be removed in 2.0
+@deprecate /(x::Number, v::AbstractVector) x*pinv(v)
+@deprecate (\)(a::AbstractVector, b::AbstractArray) pinv(a) * b

stdlib/LinearAlgebra/src/generic.jl

@@ -1134,7 +1134,6 @@ function (\)(A::AbstractMatrix, B::AbstractVecOrMat)
     return qr(A, ColumnNorm()) \ B
 end
 
-(\)(a::AbstractVector, b::AbstractArray) = pinv(a) * b
 """
     A / B
 
@@ -1163,9 +1162,6 @@ function (/)(A::AbstractVecOrMat, B::AbstractVecOrMat)
     size(A,2) != size(B,2) && throw(DimensionMismatch("Both inputs should have the same number of columns"))
     return copy(adjoint(adjoint(B) \ adjoint(A)))
 end
-# \(A::StridedMatrix,x::Number) = inv(A)*x Should be added at some point when the old elementwise version has been deprecated long enough
-# /(x::Number,A::StridedMatrix) = x*inv(A)
-/(x::Number, v::AbstractVector) = x*pinv(v)
 
 cond(x::Number) = iszero(x) ? Inf : 1.0
 cond(x::Number, p) = cond(x)

stdlib/LinearAlgebra/test/bidiag.jl

@@ -324,7 +324,7 @@ Random.seed!(1)
                     @test T*b ≈ Tfull*b
                     @test T'*b ≈ Tfull'*b
                     if relty != BigFloat # not supported by pivoted QR
-                        @test T/b' ≈ Tfull/b'
+                        @test (@test_deprecated T/b') ≈ (@test_deprecated Tfull/b')
                     end
                 end
             end

stdlib/LinearAlgebra/test/dense.jl

@@ -85,7 +85,8 @@ bimg  = randn(n,2)/2
                 @test_throws DimensionMismatch b'\b
                 @test_throws DimensionMismatch b\b'
                 @test norm(a*x - b, 1)/norm(b) < ε*κ*n*2 # Ad hoc, revisit!
-                @test zeros(eltya,n)\fill(eltya(1),n) ≈ (zeros(eltya,n,1)\fill(eltya(1),n,1))[1,1]
+                temp = @test_deprecated zeros(eltya,n)\fill(eltya(1),n)
+                @test temp ≈ (zeros(eltya,n,1)\fill(eltya(1),n,1))[1,1]
             end
 
             @testset "Test nullspace" begin
@@ -1136,6 +1137,22 @@ end
     end
 end
 
+function test_rdiv_pinv_consistency_dep(a, b)
+    temp1 = @test_deprecated /(a*b,b)
+    temp2 = @test_deprecated b/b
+    @test temp1 ≈ (a*temp2) ≈ (a*b)*pinv(b) ≈ a*(b*pinv(b))
+    @test typeof(temp1) == a*(typeof(temp2)) == typeof((a*b)*pinv(b)) == typeof(a*(b*pinv(b)))
+end
+function test_ldiv_pinv_consistency_dep(a, b)
+    temp1 = @test_deprecated \(a,a*b)
+    temp2 = @test_deprecated \(a,a)
+    @test temp1 ≈ temp2*b ≈ (pinv(a)*a)*b ≈ pinv(a)*(a*b)
+    @test typeof(temp1) == typeof((temp2*b)) == typeof((pinv(a)*a)*b) == typeof(pinv(a)*(a*b))
+end
+function test_div_pinv_consistency_dep(a, b)
+    test_rdiv_pinv_consistency_dep(a, b)
+    test_ldiv_pinv_consistency_dep(a, b)
+end
 function test_rdiv_pinv_consistency(a, b)
     @test (a*b)/b ≈ a*(b/b) ≈ (a*b)*pinv(b) ≈ a*(b*pinv(b))
     @test typeof((a*b)/b) == typeof(a*(b/b)) == typeof((a*b)*pinv(b)) == typeof(a*(b*pinv(b)))
@@ -1156,13 +1173,15 @@ end
         cm = rand(elty, 5, 1)
         rm = rand(elty, 1, 5)
         @testset "dot products" begin
-            test_div_pinv_consistency(r, c)
-            test_div_pinv_consistency(rm, c)
-            test_div_pinv_consistency(r, cm)
+            test_div_pinv_consistency_dep(r, c)
+            test_rdiv_pinv_consistency_dep(rm, c)
+            test_ldiv_pinv_consistency(rm, c)
+            test_rdiv_pinv_consistency(r, cm)
+            test_ldiv_pinv_consistency_dep(r, cm)
             test_div_pinv_consistency(rm, cm)
         end
         @testset "outer products" begin
-            test_div_pinv_consistency(c, r)
+            test_div_pinv_consistency_dep(c, r)
             test_div_pinv_consistency(cm, rm)
         end
         @testset "matrix/vector" begin

stdlib/LinearAlgebra/test/qr.jl

@@ -247,7 +247,9 @@ end
     # @test qr(Int[]) == (Int[],1)
 
     B = rand(7,2)
-    @test (1:7)\B ≈ Vector(1:7)\B
+    x = @test_deprecated ((1:7)\B)
+    y = @test_deprecated (Vector(1:7)\B)
+    @test x ≈ y
 end
 
 @testset "Issue 16520" begin