'''
Created on 28. aug. 2015
@author: pab
'''
import unittest
import numpy as np
from numpy.testing import assert_array_almost_equal, assert_allclose
from numdifftools.limits import Limit
[docs]class TestLimit(unittest.TestCase):
def test_sinx_divx(self):
def f(x):
return np.sin(x)/x
limf = Limit(f, full_output=True)
lim, err = limf(0)
assert_array_almost_equal(lim, 1)
self.assertTrue(err.error_estimate < 1.77249444610966e-15)
def test_derivative_of_cos(self):
x0 = np.pi/2
def g(x):
return (np.cos(x0+x)-np.cos(x0))/x
lim, err = Limit(g, full_output=True)(0)
assert_allclose(lim, -1)
self.assertTrue(err.error_estimate < 1e-14)
def test_residue(self):
def h(z):
return -z/(np.expm1(2*z))
lim, err = Limit(h, full_output=True)(0)
assert_allclose(lim, -0.5)
self.assertTrue(err.error_estimate < 1e-14)
def test_difficult_limit(self):
def k(x):
return (x*np.exp(x)-np.exp(x)+1)/x**2
lim, err = Limit(k, full_output=True)(0)
assert_allclose(lim, 0.5)
self.assertTrue(err.error_estimate < 1e-8)
if __name__ == "__main__":
unittest.main()