clean up

Author: ChrisRackauckas

docs/src/basics/Preconditioners.md

@@ -63,7 +63,6 @@ preconditioners written to match the required interface.
   preconditioner, defined as a diagonal matrix `Diagonal(1./s)`.
 - `ComposePreconditioner(prec1,prec2)`: composes the preconditioners to apply
   `prec1` before `prec2`.
-- `InvComposePreconditioner(prec1,prec2)`: only god knows what this is for.
 
 ## Preconditioner Interface
 

src/default.jl

@@ -103,7 +103,7 @@ function init_cacheval(alg::Nothing, A, b, u, Pl, Pr, maxiters, abstol, reltol,
 
     # Not factorizable operator, default to only using A*x
     # IterativeSolvers is faster on CPU but not GPU-compatible
-    elseif cache.u isa Array
+    elseif u isa Array
         alg = IterativeSolversJL_GMRES()
         init_cacheval(alg, A, b, u, Pl, Pr, maxiters, abstol, reltol, verbose)
     else

src/preconditioners.jl

@@ -78,6 +78,9 @@ function LinearAlgebra.ldiv!(y, A::ComposePreconditioner, x)
     ldiv!(outer, y)
 end
 
+# This is just an implementation detail for Krylov.jl
+# It wants to use mul! instead of ldiv! so we convert.
+
 struct InvComposePreconditioner{Tp <: ComposePreconditioner}
     P::Tp
 end