def test_diff_equation_exponential_euler(self):
eq = DifferentialEquation('dy/dt = 0+(1)*y : float')
eq.select("Exponential Euler")
y, t,dt = 1.0, 1.0, 0.01
for i in range(int(t/dt)):
y = eq.evaluate(y, dt)
assert abs(y-np.exp(1)) < 0.0001
def test_diff_equation_runge_kutta_2(self):
eq = DifferentialEquation('dy/dt = y : float')
eq.select("Runge Kutta 2")
y, t,dt = 1.0, 1.0, 0.001
for i in range(int(t/dt)):
y = eq.evaluate(y, dt)
assert abs(y-np.exp(1)) < 0.0001
def test(): eq = DifferentialEquation('y=1')
self.assertRaises(DifferentialEquationError,test)
def test_exponential_form_3(self):
eq = DifferentialEquation('dy/dt = (1.3)*y')
assert eq._A_string == '0'
assert eq._B_string == '-1.3'
def test_exponential_form_1(self):
eq = DifferentialEquation('dy/dt = 1.2+(3.4)*y')
assert eq._A_string == '1.2'
assert eq._B_string == '-3.4'
def test_standard_form_4(self):
eq = DifferentialEquation('dy/dt = 1.2+(3.4)*y')
assert eq._varname == 'y'
assert eq._dtype == 'float'
def test_standard_form_3(self):
eq = DifferentialEquation('dy/dt = 1.0 : int')
assert eq._varname == 'y'
assert eq._dtype == 'int'