Merge pull request #1213 from lamorton/comparisons

Handle conditionals & comparisons correctly in unit validation.

Author: ChrisRackauckas

src/systems/validation.jl

@@ -51,6 +51,15 @@ function get_unit(x::Symbolic)
             equivalent(other,firstunit) || throw(ValidationError(", in sum $x, units [$termlist] do not match."))
         end
         return firstunit
+    elseif operation(x) in ( Base.:> ,  Base.:< , == )
+        terms = get_unit.(arguments(x))
+        equivalent(terms[1],terms[2]) || throw(ValidationError(", in comparison $x, units [$(terms[1])] and [$(terms[2])] do not match."))
+        return unitless
+    elseif operation(x) == ifelse || operation(x) == IfElse.ifelse
+         terms = get_unit.(arguments(x))
+        terms[1] == unitless || throw(ValidationError(", in $x, [$(terms[1])] is not dimensionless."))
+        equivalent(terms[2],terms[3]) || throw(ValidationError(", in $x, units [$(terms[2])] and [$(terms[3])] do not match."))
+        return terms[2]
     elseif operation(x) == Symbolics._mapreduce 
         if x.arguments[2] == +
             get_unit(x.arguments[3])

test/units.jl

@@ -1,4 +1,4 @@
-using ModelingToolkit, Unitful, OrdinaryDiffEq, DiffEqJump
+using ModelingToolkit, Unitful, OrdinaryDiffEq, DiffEqJump, IfElse
 using Test
 MT = ModelingToolkit
 @parameters τ [unit = u"ms"]
@@ -196,4 +196,14 @@ maj2 = MassActionJump(γ, [I => 1], [I => -1, R => 1])
 
 maj1 = MassActionJump(2.0, [0 => 1], [S => 1])
 maj2 = MassActionJump(γ, [S => 1], [S => -1])
-@named js4  = JumpSystem([maj1, maj2], t, [S], [β, γ])
+@named js4  = JumpSystem([maj1, maj2], t, [S], [β, γ])
+
+#Test comparisons
+@parameters t
+vars = @variables x(t)
+D = Differential(t)
+eqs = 
+[
+    D(x) ~ IfElse.ifelse(t>0.1,2,1)
+]
+@named sys = ODESystem(eqs, t, vars, [])