Merge pull request #909 from SciML/myb/defaults

Allow incomplete initialization

Author: YingboMa

src/systems/diffeqs/abstractodesystem.jl

@@ -291,7 +291,9 @@ function process_DEProblem(constructor, sys::AbstractODESystem,u0map,parammap;
     u0 = varmap_to_vars(u0map,dvs; defaults=defs)
     p = varmap_to_vars(parammap,ps; defaults=defs)
 
-    length(dvs) == length(u0) || throw(ArgumentError("States ($(length(dvs))) and initial conditions ($(length(u0))) are of different lengths."))
+    if u0 !== nothing
+        length(dvs) == length(u0) || throw(ArgumentError("States ($(length(dvs))) and initial conditions ($(length(u0))) are of different lengths."))
+    end
 
     f = constructor(sys,dvs,ps,u0;tgrad=tgrad,jac=jac,checkbounds=checkbounds,
                     linenumbers=linenumbers,parallel=parallel,simplify=simplify,

src/systems/nonlinear/nonlinearsystem.jl

@@ -211,7 +211,9 @@ function process_NonlinearProblem(constructor, sys::NonlinearSystem,u0map,paramm
     u0 = varmap_to_vars(u0map,dvs; defaults=defs)
     p = varmap_to_vars(parammap,ps; defaults=defs)
 
-    length(dvs) == length(u0) || throw(ArgumentError("States ($(length(dvs))) and initial conditions ($(length(u0))) are of different lengths."))
+    if u0 !== nothing
+        length(dvs) == length(u0) || throw(ArgumentError("States ($(length(dvs))) and initial conditions ($(length(u0))) are of different lengths."))
+    end
 
     f = constructor(sys,dvs,ps,u0;jac=jac,checkbounds=checkbounds,
                     linenumbers=linenumbers,parallel=parallel,simplify=simplify,

src/variables.jl

@@ -12,9 +12,12 @@ applicable.
 """
 function varmap_to_vars(varmap, varlist; defaults=Dict(), check=true)
     # Edge cases where one of the arguments is effectively empty.
-    if varmap isa DiffEqBase.NullParameters || varmap === nothing || isempty(varmap)
+    is_incomplete_initialization = varmap isa DiffEqBase.NullParameters || varmap === nothing
+    if is_incomplete_initialization || isempty(varmap)
         if isempty(defaults)
-            check && (isempty(varlist) || throw_missingvars(varlist))
+            if !is_incomplete_initialization && check
+                isempty(varlist) || throw_missingvars(varlist)
+            end
             return nothing
         else
             varmap = Dict()

test/sdesystem.jl

@@ -29,7 +29,7 @@ solexpr = solve(eval(probexpr),SRIW1(),seed=1)
 @test all(x->x==0,Array(sol-solexpr))
 
 # Test no error
-@test_nowarn SDEProblem(de,zeros(3),(0, 10.0),zeros(3))
+@test_nowarn SDEProblem(de,nothing,(0, 10.0))
 
 noiseeqs_nd = [0.01*x 0.01*x*y 0.02*x*z
                σ      0.01*y   0.02*x*z

test/structural_transformation/tearing.jl

@@ -149,7 +149,6 @@ daesys = ODESystem(eqs, t)
 newdaesys = tearing(daesys)
 @test equations(newdaesys) == [D(x) ~ z; 0 ~ x + sin(z) - p*t]
 @test isequal(states(newdaesys), [x, z])
-@test_throws ArgumentError ODAEProblem(newdaesys, [x=>1.0], (0, 1.0))
 prob = ODAEProblem(newdaesys, [x=>1.0], (0, 1.0), [p=>0.2])
 du = [0.0]; u = [1.0]; pr = 0.2; tt = 0.1
 @test (@ballocated $(prob.f)($du, $u, $pr, $tt)) == 0