deprecate preconditioner interface and use scimloperators

Author: vpuri3

src/LinearSolve.jl

@@ -10,7 +10,9 @@ import Base: eltype, adjoint, inv
 using LinearAlgebra
 using IterativeSolvers: Identity
 using SparseArrays
-using SciMLBase: AbstractSciMLOperator, AbstractLinearAlgorithm
+using SciMLBase: AbstractLinearAlgorithm, DiffEqIdentity
+using SciMLOperators: AbstractSciMLOperator, IdentityOperator,
+                      InvertedOperator, ComposedOperator
 using Setfield
 using UnPack
 using SuiteSparse

src/iterative_wrappers.jl

@@ -151,8 +151,8 @@ function SciMLBase.solve(cache::LinearCache, alg::KrylovJL; kwargs...)
     N = cache.Pr
 
     # use no-op preconditioner for Krylov.jl (LinearAlgebra.I) when M/N is identity
-    M = _isidentity_struct(M) ? I : InvPreconditioner(M)
-    N = _isidentity_struct(M) ? I : InvPreconditioner(N)
+    M = _isidentity_struct(M) ? I : InvertedOperator(M)
+    N = _isidentity_struct(M) ? I : InvertedOperator(N)
 
     atol = float(cache.abstol)
     rtol = float(cache.reltol)

src/preconditioners.jl

@@ -1,4 +1,11 @@
 # Tooling Preconditioners
+#
+# TODO - update Preconditioner docs
+# TODO - replace ComposePreconditoner with ComposedOperator after
+#        ComposePreconditioner is deprecated in OrdinaryDiffEq
+
+#const ComposePreconditioner = ComposedOperator
+#@deprecate ComposePreconditioner ComposedOperator
 
 struct ComposePreconditioner{Ti, To}
     inner::Ti
@@ -21,11 +28,5 @@ function LinearAlgebra.ldiv!(y, A::ComposePreconditioner, x)
     ldiv!(outer, y)
 end
 
-struct InvPreconditioner{T}
-    P::T
-end
-
-Base.eltype(A::InvPreconditioner) = Base.eltype(A.P)
-LinearAlgebra.ldiv!(A::InvPreconditioner, x) = mul!(x, A.P, x)
-LinearAlgebra.ldiv!(y, A::InvPreconditioner, x) = mul!(y, A.P, x)
-LinearAlgebra.mul!(y, A::InvPreconditioner, x) = ldiv!(y, A.P, x)
+#const InvPreconditioner = InvertedOperator
+#@deprecate InvPreconditioner InvertedOperator

test/basictests.jl

@@ -271,12 +271,18 @@ end
 
     @testset "Preconditioners" begin
         @testset "Vector Diagonal Preconditioner" begin
-            s = rand(n)
-            Pl, Pr = Diagonal(s), LinearSolve.InvPreconditioner(Diagonal(s))
+            using SciMLOperators
 
             x = rand(n, n)
             y = rand(n, n)
 
+            s = rand(n)
+            Pl = Diagonal(s)
+            Pr = Diagonal(s)
+            Pr = LinearSolve.InvertedOperator(MatrixOperator(Pr))
+            Pr = cache_operator(Pr, x)
+            #@test Pr == (@test_deprecated LinearSolve.InvPreconditioner(Diagonal(s)))
+
             mul!(y, Pl, x)
             @test y ≈ s .* x
             mul!(y, Pr, x)