Fix steady state syste,s test file.

Author: TorkelE

test/steadystatesystems.jl

@@ -0,0 +1,17 @@
+using ModelingToolkit
+using DifferentialEquations
+using Test
+
+@parameters t r
+@variables x(t)
+@derivatives D'~t
+eqs = [D(x) ~ x^2-r]
+de = ODESystem(eqs)
+
+for factor in [1e-1, 1e0, 1e10], u0_p in [(2.34,2.676),(22.34,1.632),(.3,15.676),(0.3,0.006)]
+    u0 = [x => factor*u0_p[1]]
+    p = [r => factor*u0_p[2]]
+    ss_prob = SteadyStateProblem(de,u0,p)
+    sol = solve(ss_prob).u[1]
+    @test abs(sol^2 - factor*u0_p[2]) < 1e-8
+end