/
t_tools.py
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/
t_tools.py
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"""Tests for tools module"""
import unittest
import numpy as np
from numpy import log
from gpkit import Variable, VectorVariable, Model, NomialArray
from gpkit.tools.autosweep import BinarySweepTree
from gpkit.tools.tools import te_exp_minus1, te_secant, te_tangent
from gpkit.small_scripts import mag
from gpkit import parse_variables
def assert_logtol(first, second, logtol=1e-6):
"Asserts that the logs of two arrays have a given abstol"
np.testing.assert_allclose(log(mag(first)), log(mag(second)),
atol=logtol, rtol=0)
class OnlyVectorParse(Model):
"""
Variables of length 3
---------------------
x [-] just another variable
"""
@parse_variables(__doc__, globals())
def setup(self):
pass
class Fuselage(Model):
"""The thing that carries the fuel, engine, and payload
Variables
---------
f [-] Fineness
g 9.81 [m/s^2] Standard gravity
k [-] Form factor
l [ft] Length
mfac 2.0 [-] Weight margin factor
R [ft] Radius
rhocfrp 1.6 [g/cm^3] Density of CFRP
rhofuel 6.01 [lbf/gallon] Density of 100LL fuel
S [ft^2] Wetted area
t 0.024 [in] Minimum skin thickness
Vol [ft^3] Volume
W [lbf] Weight
Upper Unbounded
---------------
k, W
"""
# pylint: disable=undefined-variable, invalid-name
@parse_variables(__doc__, globals())
def setup(self, Wfueltot):
return [
f == l/R/2,
k >= 1 + 60/f**3 + f/400,
3*(S/np.pi)**1.6075 >= 2*(l*R*2)**1.6075 + (2*R)**(2*1.6075),
Vol <= 4*np.pi/3*(l/2)*R**2,
Vol >= Wfueltot/rhofuel,
W/mfac >= S*rhocfrp*t*g,
]
class TestTools(unittest.TestCase):
"""TestCase for math models"""
def test_vector_only_parse(self):
# pylint: disable=no-member
m = OnlyVectorParse()
self.assertTrue(hasattr(m, "x"))
self.assertIsInstance(m.x, NomialArray)
self.assertEqual(len(m.x), 3)
def test_parse_variables(self):
Fuselage(Variable("Wfueltot", 5, "lbf"))
def test_binary_sweep_tree(self):
bst0 = BinarySweepTree([1, 2], [{"cost": 1}, {"cost": 8}], None, None)
assert_logtol(bst0.sample_at([1, 1.5, 2])["cost"], [1, 3.375, 8], 1e-3)
bst0.add_split(1.5, {"cost": 4})
assert_logtol(bst0.sample_at([1, 1.25, 1.5, 1.75, 2])["cost"],
[1, 2.144, 4, 5.799, 8], 1e-3)
def test_dual_objective(self):
L = Variable("L")
W = Variable("W")
eqns = [L >= 1, W >= 1,
L*W == 10]
N = 4
ws = Variable("w_{CO}", ("sweep", np.linspace(1/N, 1-1/N, N)), "-")
w_s = Variable("v_{CO}", lambda c: 1-c[ws], "-")
obj = ws*(L+W) + w_s*(W**-1 * L**-3)
m = Model(obj, eqns)
sol = m.solve(verbosity=0)
a = sol["cost"]
b = np.array([1.58856898, 2.6410391, 3.69348122, 4.74591386])
self.assertTrue((abs(a-b)/(a+b+1e-7) < 1e-7).all())
def test_te_exp_minus1(self):
"""Test Taylor expansion of e^x - 1"""
x = Variable('x')
self.assertEqual(te_exp_minus1(x, 1), x)
self.assertEqual(te_exp_minus1(x, 3), x + x**2/2 + x**3/6)
self.assertEqual(te_exp_minus1(x, 0), 0)
# make sure x was not modified
self.assertEqual(x, Variable('x'))
# try for VectorVariable too
y = VectorVariable(3, 'y')
self.assertEqual(te_exp_minus1(y, 1), y)
self.assertEqual(te_exp_minus1(y, 3), y + y**2/2 + y**3/6)
self.assertEqual(te_exp_minus1(y, 0), 0)
# make sure y was not modified
self.assertEqual(y, VectorVariable(3, 'y'))
def test_te_secant(self):
"Test Taylor expansion of secant(var)"
x = Variable('x')
self.assertEqual(te_secant(x, 1), 1 + x**2/2)
a = te_secant(x, 2)
b = 1 + x**2/2 + 5*x**4/24
self.assertTrue(all([abs(val) <= 1e-10
for val in (a.hmap - b.hmap).values()])) # pylint:disable=no-member
self.assertEqual(te_secant(x, 0), 1)
# make sure x was not modified
self.assertEqual(x, Variable('x'))
# try for VectorVariable too
y = VectorVariable(3, 'y')
self.assertTrue(te_secant(y, 0) == 1) # truthy bc monomial constraint
self.assertTrue(all(te_secant(y, 1) == 1 + y**2/2))
self.assertTrue(all(te_secant(y, 2) == 1 + y**2/2 + 5*y**4/24))
# make sure y was not modified
self.assertEqual(y, VectorVariable(3, 'y'))
def test_te_tangent(self):
"Test Taylor expansion of tangent(var)"
x = Variable('x')
self.assertEqual(te_tangent(x, 1), x)
self.assertEqual(te_tangent(x, 3), x + x**3/3 + 2*x**5/15)
self.assertEqual(te_tangent(x, 0), 0)
# make sure x was not modified
self.assertEqual(x, Variable('x'))
# try for VectorVariable too
y = VectorVariable(3, 'y')
self.assertEqual(te_tangent(y, 1), y)
self.assertEqual(te_tangent(y, 3), y + y**3/3 + 2*y**5/15)
self.assertEqual(te_tangent(y, 0), 0)
# make sure y was not modified
self.assertEqual(y, VectorVariable(3, 'y'))
TESTS = [TestTools]
if __name__ == "__main__": # pragma: no cover
# pylint: disable=wrong-import-position
from gpkit.tests.helpers import run_tests
run_tests(TESTS)