def test_equation_rewrite(self):
""" Test the equation rewriting function """
variables = dict()
variables['x'] = Variable('x')
variables['y'] = Variable('y')
self.assertEquals('x - y', _rewrite(variables, {}, 'x - y'))
self.assertEquals('xx - y', _rewrite(variables, {}, 'xx - y'))
self.assertEquals('xx - yx', _rewrite(variables, {}, 'xx - yx'))
self.assertEquals('xx(0) - yx', _rewrite(variables, {}, 'xx(0) - yx'))
self.assertEquals('_series_acc(x,-1)',
_rewrite(variables, {}, 'x(-1)'))
self.assertEquals('_series_acc(x,-t)',
_rewrite(variables, {}, 'x(-t)'))
parameters = dict()
parameters['a'] = Parameter('a')
parameters['b'] = Parameter('b')
self.assertEquals('_series_acc(a,-1)', _rewrite({}, parameters,
'a(-1)'))
def test_equation_rewrite(self):
""" Test the equation rewriting function """
variables = dict()
variables['x'] = Variable('x')
variables['y'] = Variable('y')
self.assertEquals('x - y', _rewrite(variables, {}, 'x - y'))
self.assertEquals('xx - y', _rewrite(variables, {}, 'xx - y'))
self.assertEquals('xx - yx', _rewrite(variables, {}, 'xx - yx'))
self.assertEquals('xx(0) - yx', _rewrite(variables, {}, 'xx(0) - yx'))
self.assertEquals('_series_acc(x,-1)',
_rewrite(variables, {}, 'x(-1)'))
self.assertEquals('_series_acc(x,-t)',
_rewrite(variables, {}, 'x(-t)'))
parameters = dict()
parameters['a'] = Parameter('a')
parameters['b'] = Parameter('b')
self.assertEquals('_series_acc(a,-1)',
_rewrite({}, parameters, 'a(-1)'))
def evaluate(self, equation):
""" Evaluates an arbitrary function using the current values
of the variables.
Parmeters:
eqn:
Returns:
The value of the expression.
"""
equation = _rewrite(self.variables, self.parameters, equation)
expr = parse_expr(equation,
self._local_context,
transformations=(factorial_notation, auto_number))
expr = sympify(expr).subs(self._get_context())
for func in _RT_FUNCS:
expr = expr.replace(func[2], func[1])
if sympify(expr).is_number:
break
return float(expr)
def evaluate(self, equation):
""" Evaluates an arbitrary function using the current values
of the variables.
Parmeters:
eqn:
Returns:
The value of the expression.
"""
equation = _rewrite(self.variables, self.parameters, equation)
expr = parse_expr(equation,
self._local_context,
transformations=(factorial_notation, auto_number))
expr = sympify(expr).subs(self._get_context())
for func in _RT_FUNCS:
expr = expr.replace(func[2], func[1])
if sympify(expr).is_number:
break
return float(expr)