Wrap (ParCSR)GMRES solver.

gen/solver_options.jl

@@ -51,5 +51,6 @@ open(joinpath(@__DIR__, "..", "src", "solver_options.jl"), "w") do io
     println(io, "Internals.set_options(::HYPRESolver, kwargs) = nothing")
 
     generate_options(io, "BoomerAMG", "HYPRE_BoomerAMGSet")
+    generate_options(io, "GMRES", "HYPRE_ParCSRGMRESSet", "HYPRE_GMRESSet")
     generate_options(io, "PCG", "HYPRE_ParCSRPCGSet", "HYPRE_PCGSet")
 end

src/solver_options.jl

@@ -259,6 +259,37 @@ function Internals.set_options(s::BoomerAMG, kwargs)
     end
 end
 
+function Internals.set_options(s::GMRES, kwargs)
+    solver = s.solver
+    for (k, v) in kwargs
+        if k === :ConvergenceFactorTol
+            @check HYPRE_GMRESSetConvergenceFactorTol(solver, v)
+        elseif k === :RelChange
+            @check HYPRE_GMRESSetRelChange(solver, v)
+        elseif k === :SkipRealResidualCheck
+            @check HYPRE_GMRESSetSkipRealResidualCheck(solver, v)
+        elseif k === :AbsoluteTol
+            @check HYPRE_ParCSRGMRESSetAbsoluteTol(solver, v)
+        elseif k === :KDim
+            @check HYPRE_ParCSRGMRESSetKDim(solver, v)
+        elseif k === :Logging
+            @check HYPRE_ParCSRGMRESSetLogging(solver, v)
+        elseif k === :MaxIter
+            @check HYPRE_ParCSRGMRESSetMaxIter(solver, v)
+        elseif k === :MinIter
+            @check HYPRE_ParCSRGMRESSetMinIter(solver, v)
+        elseif k === :Precond
+            Internals.set_precond(s, v)
+        elseif k === :PrintLevel
+            @check HYPRE_ParCSRGMRESSetPrintLevel(solver, v)
+        elseif k === :StopCrit
+            @check HYPRE_ParCSRGMRESSetStopCrit(solver, v)
+        elseif k === :Tol
+            @check HYPRE_ParCSRGMRESSetTol(solver, v)
+        end
+    end
+end
+
 function Internals.set_options(s::PCG, kwargs)
     solver = s.solver
     for (k, v) in kwargs

src/solvers.jl

@@ -81,6 +81,42 @@ Internals.solve_func(::BoomerAMG) = HYPRE_BoomerAMGSolve
 Internals.setup_func(::BoomerAMG) = HYPRE_BoomerAMGSetup
 
 
+#########
+# GMRES #
+#########
+
+mutable struct GMRES <: HYPRESolver
+    solver::HYPRE_Solver
+    function GMRES(comm::MPI.Comm=MPI.COMM_WORLD; kwargs...)
+        solver = new(C_NULL)
+        solver_ref = Ref{HYPRE_Solver}(C_NULL)
+        @check HYPRE_ParCSRGMRESCreate(comm, solver_ref)
+        solver.solver = solver_ref[]
+        # Attach a finalizer
+        finalizer(x -> HYPRE_ParCSRGMRESDestroy(x.solver), solver)
+        # Set the options
+        Internals.set_options(solver, kwargs)
+        return solver
+    end
+end
+
+function solve!(gmres::GMRES, x::HYPREVector, A::HYPREMatrix, b::HYPREVector)
+    @check HYPRE_ParCSRGMRESSetup(gmres.solver, A.ParCSRMatrix, b.ParVector, x.ParVector)
+    @check HYPRE_ParCSRGMRESSolve(gmres.solver, A.ParCSRMatrix, b.ParVector, x.ParVector)
+    return x
+end
+
+Internals.solve_func(::GMRES) = HYPRE_ParCSRGMRESSetup
+Internals.setup_func(::GMRES) = HYPRE_ParCSRGMRESSolve
+
+function Internals.set_precond(gmres::GMRES, p::HYPRESolver)
+    solve_f = Internals.solve_func(p)
+    setup_f = Internals.setup_func(p)
+    @check HYPRE_ParCSRGMRESSetPrecond(gmres.solver, solve_f, setup_f, p.solver)
+    return nothing
+end
+
+
 ###############
 # (ParCSR)PCG #
 ###############

test/runtests.jl

@@ -297,6 +297,40 @@ end
     @test x ≈ A \ b atol=tol
 end
 
+@testset "GMRES" begin
+    # 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.GMRES(; 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(; MaxIter = 1, Tol = 0.0)
+    gmres = HYPRE.GMRES(; 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 "(ParCSR)PCG" begin
     # Setup
     A = sprand(100, 100, 0.05); A = A'A + 5I