Merge pull request #1019 from SciML/sparse

fix and test sparse return

Author: YingboMa

src/systems/diffeqs/abstractodesystem.jl

@@ -221,7 +221,7 @@ function DiffEqBase.ODEFunction{iip}(sys::AbstractODESystem, dvs = states(sys),
                      jac = _jac === nothing ? nothing : _jac,
                      tgrad = _tgrad === nothing ? nothing : _tgrad,
                      mass_matrix = _M,
-                     jac_prototype = (!isnothing(u0) && sparse) ? (!jac ? similar(jacobian_sparsity(sys),uElType) : similar(get_jac(sys)[],uElType)) : nothing,
+                     jac_prototype = (!isnothing(u0) && sparse) ? (!jac ? similar(jacobian_sparsity(sys),uElType) : SparseArrays.sparse(similar(get_jac(sys)[],uElType))) : nothing,
                      syms = Symbol.(states(sys)),
                      indepsym = Symbol(independent_variable(sys)),
                      observed = observedfun,

test/odesystem.jl

@@ -225,6 +225,7 @@ for p in [prob1, prob14]
 end
 prob2 = ODEProblem(sys,u0,tspan,p,jac=true)
 prob3 = ODEProblem(sys,u0,tspan,p,jac=true,sparse=true)
+@test prob3.f.sparsity isa SparseMatrixCSC
 @test_throws ArgumentError ODEProblem(sys,zeros(5),tspan,p)
 for (prob, atol) in [(prob1, 1e-12), (prob2, 1e-12), (prob3, 1e-12)]
     local sol