Fix and test reuse_symbolic=false for UMFPACK lu!() (#712)

The `reuse_symbolic=false` option for UMFPACK's `lu!()` is broken, due
to undefined `Tv` and `Ti`. This PR fixes that bug, and adds a test that
uses `reuse_symbolic=false`.

Author: johnomotani

src/solvers/umfpack.jl

@@ -471,7 +471,8 @@ function lu!(F::UmfpackLU{Tv, Ti}, S::AbstractSparseMatrixCSC;
     return lu!(F; reuse_symbolic, check, q)
 end
 
-function lu!(F::UmfpackLU; check::Bool=true, reuse_symbolic::Bool=true, q=nothing)
+function lu!(F::UmfpackLU{Tv, Ti}; check::Bool=true, reuse_symbolic::Bool=true,
+  q=nothing) where {Tv, Ti}
     if !reuse_symbolic && _isnotnull(F.symbolic)
         F.symbolic = Symbolic{Tv, Ti}(C_NULL)
     end

test/umfpack.jl

@@ -408,7 +408,7 @@ end
         umfpack_report(x.b)
     end
 
-    @testset "Reuse symbolic LU factorization" begin
+    @testset "Do/do not reuse symbolic LU factorization" for reuse ∈ (true, false)
         A1 = sparse(increment!([0,4,1,1,2,2,0,1,2,3,4,4]),
                     increment!([0,4,0,2,1,2,1,4,3,2,1,2]),
                     [2.,1.,3.,4.,-1.,-3.,3.,9.,2.,1.,4.,2.], 5, 5)
@@ -420,7 +420,7 @@ end
                 b = Tv[8., 45., -3., 3., 19.]
                 F = lu(A)
                 umfpack_report(F)
-                lu!(F, B)
+                lu!(F, B; reuse_symbolic=reuse)
                 umfpack_report(F)
                 @test F\b ≈ B\b ≈ Matrix(B)\b
 
@@ -429,14 +429,20 @@ end
                 C[4, 3] = Tv(0)
                 F = lu(A)
                 umfpack_report(F)
-                @test_throws SingularException lu!(F, C)
+                @test_throws SingularException lu!(F, C; reuse_symbolic=reuse)
                 # change of nonzero pattern
                 D = copy(B)
                 D[5, 1] = Tv(1.0)
                 F = lu(A)
                 umfpack_report(F)
-                @test_throws ArgumentError lu!(F, D)
-                umfpack_report(F)
+                if reuse
+                    @test_throws ArgumentError lu!(F, D; reuse_symbolic=reuse)
+                    umfpack_report(F)
+                else
+                    lu!(F, D; reuse_symbolic=reuse)
+                    umfpack_report(F)
+                    @test F\b ≈ D\b ≈ Matrix(D)\b
+                end
             end
         end
     end