Add FlexGMRES solver.

gen/solver_options.jl

@@ -55,6 +55,7 @@ open(joinpath(@__DIR__, "..", "src", "solver_options.jl"), "w") do io
 
     generate_options(io, "BiCGSTAB", "HYPRE_ParCSRBiCGSTABSet", "HYPRE_BiCGSTABSet")
     generate_options(io, "BoomerAMG", "HYPRE_BoomerAMGSet")
+    generate_options(io, "FlexGMRES", "HYPRE_ParCSRFlexGMRESSet", "HYPRE_FlexGMRESSet")
     # generate_options(io, "FSAI", "HYPRE_FSAISet")
     generate_options(io, "GMRES", "HYPRE_ParCSRGMRESSet", "HYPRE_GMRESSet")
     generate_options(io, "ILU", "HYPRE_ILUSet")

src/solver_options.jl

@@ -289,6 +289,36 @@ function Internals.set_options(s::BoomerAMG, kwargs)
     end
 end
 
+function Internals.set_options(s::FlexGMRES, kwargs)
+    solver = s.solver
+    for (k, v) in kwargs
+        if k === :ConvergenceFactorTol
+            @check HYPRE_FlexGMRESSetConvergenceFactorTol(solver, v)
+        elseif k === :AbsoluteTol
+            @check HYPRE_ParCSRFlexGMRESSetAbsoluteTol(solver, v)
+        elseif k === :KDim
+            @check HYPRE_ParCSRFlexGMRESSetKDim(solver, v)
+        elseif k === :Logging
+            @check HYPRE_ParCSRFlexGMRESSetLogging(solver, v)
+        elseif k === :MaxIter
+            @check HYPRE_ParCSRFlexGMRESSetMaxIter(solver, v)
+        elseif k === :MinIter
+            @check HYPRE_ParCSRFlexGMRESSetMinIter(solver, v)
+        elseif k === :ModifyPC
+            @check HYPRE_ParCSRFlexGMRESSetModifyPC(solver, v)
+        elseif k === :Precond
+            Internals.set_precond_defaults(v)
+            Internals.set_precond(s, v)
+        elseif k === :PrintLevel
+            @check HYPRE_ParCSRFlexGMRESSetPrintLevel(solver, v)
+        elseif k === :Tol
+            @check HYPRE_ParCSRFlexGMRESSetTol(solver, v)
+        else
+            throw(ArgumentError("unknown option $k for HYPRE.FlexGMRES"))
+        end
+    end
+end
+
 function Internals.set_options(s::GMRES, kwargs)
     solver = s.solver
     for (k, v) in kwargs

src/solvers.jl

@@ -152,6 +152,44 @@ function Internals.set_precond_defaults(amg::BoomerAMG)
 end
 
 
+#############
+# FlexGMRES #
+#############
+
+mutable struct FlexGMRES <: HYPRESolver
+    comm::MPI.Comm
+    solver::HYPRE_Solver
+    function FlexGMRES(comm::MPI.Comm=MPI.COMM_NULL; kwargs...)
+        # comm defaults to COMM_NULL since it is unused in HYPRE_ParCSRFlexGMRESCreate
+        solver = new(comm, C_NULL)
+        solver_ref = Ref{HYPRE_Solver}(C_NULL)
+        @check HYPRE_ParCSRFlexGMRESCreate(comm, solver_ref)
+        solver.solver = solver_ref[]
+        # Attach a finalizer
+        finalizer(x -> HYPRE_ParCSRFlexGMRESDestroy(x.solver), solver)
+        # Set the options
+        Internals.set_options(solver, kwargs)
+        return solver
+    end
+end
+
+function solve!(flex::FlexGMRES, x::HYPREVector, A::HYPREMatrix, b::HYPREVector)
+    @check HYPRE_ParCSRFlexGMRESSetup(flex.solver, A.parmatrix, b.parvector, x.parvector)
+    @check HYPRE_ParCSRFlexGMRESSolve(flex.solver, A.parmatrix, b.parvector, x.parvector)
+    return x
+end
+
+Internals.setup_func(::FlexGMRES) = HYPRE_ParCSRFlexGMRESSetup
+Internals.solve_func(::FlexGMRES) = HYPRE_ParCSRFlexGMRESSolve
+
+function Internals.set_precond(flex::FlexGMRES, p::HYPRESolver)
+    solve_f = Internals.solve_func(p)
+    setup_f = Internals.setup_func(p)
+    @check HYPRE_ParCSRFlexGMRESSetPrecond(flex.solver, solve_f, setup_f, p.solver)
+    return nothing
+end
+
+
 #########
 ## FSAI #
 #########

test/runtests.jl

@@ -370,6 +370,46 @@ end
     @test x ≈ A \ b atol=tol
 end
 
+@testset "FlexGMRES" begin
+    # Solver constructor and options
+    @test_throws(
+        ArgumentError("unknown option UnknownOption for HYPRE.FlexGMRES"),
+        HYPRE.FlexGMRES(; UnknownOption = 1)
+    )
+    # Setup
+    A = sprand(100, 100, 0.05); A = A'A + 5I
+    b = rand(100)
+    x = zeros(100)
+    A_h = HYPREMatrix(A)
+    b_h = HYPREVector(b)
+    x_h = HYPREVector(x)
+    # Solve
+    tol = 1e-9
+    gmres = HYPRE.FlexGMRES(; Tol = tol)
+    HYPRE.solve!(gmres, x_h, A_h, b_h)
+    copy!(x, x_h)
+    # Test result with direct solver
+    @test x ≈ A \ b atol=tol
+    # Test without passing initial guess
+    x_h = HYPRE.solve(gmres, A_h, b_h)
+    copy!(x, x_h)
+    @test x ≈ A \ b atol=tol
+
+    # Solve with preconditioner
+    precond = HYPRE.BoomerAMG()
+    gmres = HYPRE.FlexGMRES(; Tol = tol, Precond = precond)
+    x_h = HYPREVector(zeros(100))
+    HYPRE.solve!(gmres, x_h, A_h, b_h)
+    copy!(x, x_h)
+    # Test result with direct solver
+    @test x ≈ A \ b atol=tol
+    # Test without passing initial guess
+    x_h = HYPRE.solve(gmres, A_h, b_h)
+    copy!(x, x_h)
+    @test x ≈ A \ b atol=tol
+end
+
+
 @testset "GMRES" begin
     # Solver constructor and options
     @test_throws(