Resolved bug for zero-valued differential equations declared in eleme…

…ntary form, by creating an dummy constant-like enode

src/sloth/core/equation.py

@@ -7,6 +7,7 @@
 """
 
 from .expression_evaluation import EquationNode
+from .template_units import dimless
 from .error_definitions import UnexpectedValueError, AbsentRequiredObjectError, UnresolvedPanicError
 import sympy as sp
 
@@ -28,7 +29,7 @@ class Equation:
     Definition of Equation class. Process the ExpressionNode into one resultant node, which can be evaluated.
     """
 
-    def __init__(self, name, description, fast_expr = None, owner_model_name=""):
+    def __init__(self, name, description, fast_expr=None, owner_model_name=""):
 
         """
         Istantiate Equation.
@@ -51,6 +52,8 @@ def __init__(self, name, description, fast_expr = None, owner_model_name=""):
 
             name = gen_rnd_str()
 
+        #print("===> fast_expr = ", fast_expr,", owner_model_name = ", owner_model_name)
+
         self.name = name
 
         self.description = description
@@ -67,9 +70,9 @@ def __init__(self, name, description, fast_expr = None, owner_model_name=""):
 
         self.objects_declared = {}
 
-        if fast_expr != None:
+        if fast_expr is not None:
 
-            self.setResidual( fast_expr )
+            self.setResidual(fast_expr)
 
         self.owner_model_name = owner_model_name
 
@@ -346,15 +349,30 @@ def setResidual(self, equation_expression):
 
         """
 
-        if isinstance(equation_expression, tuple) and \
-           isinstance(equation_expression[0],EquationNode) and \
-           isinstance(equation_expression[1], EquationNode):
+        if isinstance(equation_expression, tuple) and isinstance(equation_expression[0], EquationNode):
 
             # The equation expression is in the elementary form
 
-            self.elementary_equation_expression = tuple([equation_expression[0], equation_expression[1]])
+            if isinstance(equation_expression[1], EquationNode):
+
+                #If the RHS is an ENODE, pass it directly
+
+                self.elementary_equation_expression = tuple([equation_expression[0], equation_expression[1]])
+
+                self.equation_expression = equation_expression[0] - equation_expression[1]
+
+            if isinstance(equation_expression[1], float) or isinstance(equation_expression[1], int):
 
-            self.equation_expression = equation_expression[0] - equation_expression[1]
+                #If the RHS is a float or an int, convert it to ENODE previously
+
+                equation_expression1_as_enode = EquationNode(name='constant'+gen_rnd_str(),
+                                                             symbolic_object=equation_expression[1],
+                                                             unit_object=equation_expression[0].unit_object,
+                                                             repr_symbolic=equation_expression[1])
+
+                self.elementary_equation_expression = tuple([equation_expression[0], equation_expression1_as_enode])
+
+                self.equation_expression = equation_expression[0] - equation_expression1_as_enode
 
             self.equation_form = 'elementary'
 
@@ -410,7 +428,7 @@ def eval(self, symbolic_map=None, side=None):
 
         if symbolic_map == None:
 
-            symbolic_map = self.equation_expression.symbolic_map
+            symbolic_map_ = self.equation_expression.symbolic_map
 
         else:
 
@@ -422,9 +440,7 @@ def eval(self, symbolic_map=None, side=None):
 
         eval_map = dict( ( (i,j) for i, j in zip(eq_keys,eq_values) ) )
 
-        #Check if the equation expression is a float. If so, returns it directly
-
-        if isinstance(equation_expression_.symbolic_object, float):
+        if isinstance(equation_expression_.symbolic_object, float) or isinstance(equation_expression_.symbolic_object, int):
 
             res = equation_expression_.symbolic_object
 

src/sloth/core/error_definitions.py

@@ -80,6 +80,8 @@ def __str__(self):
 
         msg = "Unexpected value error. A %s was expected, but one divergent type was supplied." % (self.expected_type)
 
+        return msg
+
 class UnresolvedPanicError(Exception):
 
     """

src/sloth/core/expression_evaluation.py

@@ -18,7 +18,8 @@ class EquationNode:
           Eg: IfThen(CONDITION, [THEN_CLAUSE,ELSE_CAUSE]) 
     """
 
-    def __init__(self, name='', symbolic_object=None, symbolic_map={}, variable_map={}, is_linear=True, is_nonlinear=False, is_differential=False, unit_object=None, args=[], latex_text='', repr_symbolic=None):
+    def __init__(self, name='', symbolic_object=None, symbolic_map={}, variable_map={}, is_linear=True, is_nonlinear=False,
+                 is_differential=False, unit_object=None, args=[], latex_text='', repr_symbolic=None):
 
         """
         Instantiate EquationNode
@@ -65,8 +66,8 @@ def __init__(self, name='', symbolic_object=None, symbolic_map={}, variable_map=
 
         self.variable_map = variable_map
 
-        self.equation_type = {'is_linear':is_linear, \
-                              'is_nonlinear':is_nonlinear, \
+        self.equation_type = {'is_linear':is_linear,
+                              'is_nonlinear':is_nonlinear,
                               'is_differential':is_differential
                              }
 
@@ -139,13 +140,13 @@ def __eq__(self, other_obj):
         :rtype tuple(EquationNode, EquationNode):
         """
 
-        if isinstance(other_obj, self.__class__):
+        if isinstance(other_obj, self.__class__) or isinstance(other_obj, int) or isinstance(other_obj, float):
 
             return tuple([self, other_obj])
 
         else:
 
-            return UnexpectedValueError("EquationNode")
+            raise UnexpectedValueError("EquationNode")
 
     def __add__(self, other_obj):
 

src/sloth/model.py

@@ -836,7 +836,7 @@ def createEquation(self, name, description="", expr=None, check_equation=True):
         """
 
         eq = Equation(name, description, expr, owner_model_name=self.name)
-        eq.setResidual(expr) # I DON'T UNDERSTAND WHY THIS NEED TO BE HERE! x)
+        #eq.setResidual(expr) # I DON'T UNDERSTAND WHY THIS NEED TO BE HERE! x)
 
         eq.name=eq.name+'_'+self.name
 

tests/test_differential_model.py

@@ -62,7 +62,7 @@ def DeclareEquations(self):
 
             expr2 = self.v.Diff(self.t) ==  self.d()*self.b()*self.u()*self.v() -self.c()*self.v()
 
-            expr3 = self.y.Diff(self.t) == self.z()
+            expr3 = self.y.Diff(self.t) == 0.
 
             self.eq1 = self.createEquation("eq1", "Equation 1", expr1)
             self.eq2 = self.createEquation("eq2", "Equation 2", expr2)
@@ -266,18 +266,24 @@ def test_equation_zero_variable(mod_zero, prob, sim, compile_equations):
 
     result = sim.getResults('dict')
 
-    #assert result['t_D0']['Time(t)'][0] == pytest.approx(0.)
+    assert result['t_D0']['Time(t)'][0] == pytest.approx(0.)
 
-    #assert result['t_D0']['Time(t)'][-1] == pytest.approx(16.)
+    assert result['t_D0']['Time(t)'][-1] == pytest.approx(16.)
 
-    #assert result['t_D0']['Preys(u)'][0] == pytest.approx(10.)
+    assert result['t_D0']['Scum(y)'][0] == pytest.approx(0.)
 
-    #assert result['t_D0']['Preys(u)'][-1] == pytest.approx(8.38505427)
+    assert result['t_D0']['Scum(y)'][-1] == pytest.approx(0.)
 
-    #assert result['t_D0']['Predators(v)'][0] == pytest.approx(5.)
+    assert result['t_D0']['Preys(u)'][0] == pytest.approx(10.)
 
-    #assert result['t_D0']['Predators(v)'][-1] == pytest.approx(7.1602100083)
+    assert result['t_D0']['Preys(u)'][-1] == pytest.approx(8.38505427)
+
+    assert result['t_D0']['Predators(v)'][0] == pytest.approx(5.)
+
+    assert result['t_D0']['Predators(v)'][-1] == pytest.approx(7.1602100083)
 
     sim.showResults()
 
-    assert False
+    #assert False
+
+    #Removed ridiculously wrong test for zero-valued differential equations

tests/test_linear_model.py

@@ -30,10 +30,10 @@ def __init__(self, name, description):
 
             super().__init__(name, description)
 
-            self.a =  self.createVariable("a", kg, "A")
-            self.b =  self.createVariable("b", kg, "B")
-            self.c =  self.createVariable("c", kg, "C", is_exposed=True, type='output')            
-            self.d =  self.createVariable("d", kg, "D", is_exposed=True, type='output')
+            self.a = self.createVariable("a", kg, "A")
+            self.b = self.createVariable("b", kg, "B")
+            self.c = self.createVariable("c", kg, "C", is_exposed=True, type='output')
+            self.d = self.createVariable("d", kg, "D", is_exposed=True, type='output')
 
         def DeclareEquations(self):
 
@@ -117,7 +117,7 @@ def __init__(self, name, description):
 
 def test_model_properties(mod1):
 
-    mod=mod1
+    mod = mod1
 
     assert mod.name == "L0"