FEM: equation objects, add some comments for linear and nonlinear equation

src/Mod/Fem/femsolver/elmer/equations/linear.py

@@ -29,6 +29,11 @@ __url__ = "http://www.freecadweb.org"
 from . import equation
 
 
+# the linear equation object defines some attributes for some various elmer equations
+# these various elmer equations are based on the linear equation object
+# thus in ObjectsFem module is no method to add a linear equation object
+
+
 LINEAR_SOLVER = ["Direct", "Iterative"]
 LINEAR_DIRECT = ["Banded", "umfpack"]
 LINEAR_ITERATIVE = [

src/Mod/Fem/femsolver/elmer/equations/nonlinear.py

@@ -29,6 +29,11 @@ __url__ = "http://www.freecadweb.org"
 from . import linear
 
 
+# the linear equation object defines some attributes for some various elmer equations
+# these various elmer equations are based on the linear equation object
+# thus in ObjectsFem module is no method to add a linear equation object
+
+
 class Proxy(linear.Proxy):
 
     def __init__(self, obj):

src/Mod/Fem/femtest/testcommon.py

@@ -332,7 +332,8 @@ class FemTest(unittest.TestCase):
         self.assertEqual('Fem::FemEquationElmerFluxsolver', typeOfObj(ObjectsFem.makeEquationFluxsolver(doc, solverelmer)))
         self.assertEqual('Fem::FemEquationElmerHeat', typeOfObj(ObjectsFem.makeEquationHeat(doc, solverelmer)))
         # is = 43 (just copy in empty file to test)
-        # TODO: equation linear missing, equation nonlinear missing, use different type for fluid and solid material
+        # TODO: vtk post objs
+        # TODO: use different type for fluid and solid material
 
     def test_femobjects_isoftypenew(self):
         doc = self.active_doc