add docstring

Author: baggepinnen

src/systems/abstractsystem.jl

@@ -1386,7 +1386,7 @@ lsys = ModelingToolkit.reorder_states(lsys, states(ssys), desired_order)
 function linearize(sys, lin_fun; t = 0.0, op = Dict(), allow_input_derivatives = false,
                    p = DiffEqBase.NullParameters())
     x0 = merge(defaults(sys), op)
-    u0, p2, _ = get_u0_p(sys, x0, p; use_union = false, tofloat=true)
+    u0, p2, _ = get_u0_p(sys, x0, p; use_union = false, tofloat = true)
 
     linres = lin_fun(u0, p2, t)
     f_x, f_z, g_x, g_z, f_u, g_u, h_x, h_z, h_u = linres

src/systems/diffeqs/abstractodesystem.jl

@@ -570,6 +570,11 @@ function ODEFunctionExpr{iip}(sys::AbstractODESystem, dvs = states(sys),
     !linenumbers ? striplines(ex) : ex
 end
 
+"""
+    u0, p, defs = get_u0_p(sys, u0map, parammap; tofloat, use_union)
+
+Take dictionaries with initial conditions and parameters and convert them to numeric arrays `u0` and `p`. Also return the merged dictionary `defs` containing the entire operating point. 
+"""
 function get_u0_p(sys, u0map, parammap; tofloat, use_union)
     eqs = equations(sys)
     dvs = states(sys)