projektAI/venv/Lib/site-packages/scipy/optimize/tests/test_cython_optimize.py
2021-06-06 22:13:05 +02:00

93 lines
2.6 KiB
Python

"""
Test Cython optimize zeros API functions: ``bisect``, ``ridder``, ``brenth``,
and ``brentq`` in `scipy.optimize.cython_optimize`, by finding the roots of a
3rd order polynomial given a sequence of constant terms, ``a0``, and fixed 1st,
2nd, and 3rd order terms in ``args``.
.. math::
f(x, a0, args) = ((args[2]*x + args[1])*x + args[0])*x + a0
The 3rd order polynomial function is written in Cython and called in a Python
wrapper named after the zero function. See the private ``_zeros`` Cython module
in `scipy.optimize.cython_optimze` for more information.
"""
import numpy.testing as npt
from scipy.optimize.cython_optimize import _zeros
# CONSTANTS
# Solve x**3 - A0 = 0 for A0 = [2.0, 2.1, ..., 2.9].
# The ARGS have 3 elements just to show how this could be done for any cubic
# polynomial.
A0 = tuple(-2.0 - x/10.0 for x in range(10)) # constant term
ARGS = (0.0, 0.0, 1.0) # 1st, 2nd, and 3rd order terms
XLO, XHI = 0.0, 2.0 # first and second bounds of zeros functions
# absolute and relative tolerances and max iterations for zeros functions
XTOL, RTOL, MITR = 0.001, 0.001, 10
EXPECTED = [(-a0) ** (1.0/3.0) for a0 in A0]
# = [1.2599210498948732,
# 1.2805791649874942,
# 1.300591446851387,
# 1.3200061217959123,
# 1.338865900164339,
# 1.3572088082974532,
# 1.375068867074141,
# 1.3924766500838337,
# 1.4094597464129783,
# 1.4260431471424087]
# test bisect
def test_bisect():
npt.assert_allclose(
EXPECTED,
list(
_zeros.loop_example('bisect', A0, ARGS, XLO, XHI, XTOL, RTOL, MITR)
),
rtol=RTOL, atol=XTOL
)
# test ridder
def test_ridder():
npt.assert_allclose(
EXPECTED,
list(
_zeros.loop_example('ridder', A0, ARGS, XLO, XHI, XTOL, RTOL, MITR)
),
rtol=RTOL, atol=XTOL
)
# test brenth
def test_brenth():
npt.assert_allclose(
EXPECTED,
list(
_zeros.loop_example('brenth', A0, ARGS, XLO, XHI, XTOL, RTOL, MITR)
),
rtol=RTOL, atol=XTOL
)
# test brentq
def test_brentq():
npt.assert_allclose(
EXPECTED,
list(
_zeros.loop_example('brentq', A0, ARGS, XLO, XHI, XTOL, RTOL, MITR)
),
rtol=RTOL, atol=XTOL
)
# test brentq with full output
def test_brentq_full_output():
output = _zeros.full_output_example(
(A0[0],) + ARGS, XLO, XHI, XTOL, RTOL, MITR)
npt.assert_allclose(EXPECTED[0], output['root'], rtol=RTOL, atol=XTOL)
npt.assert_equal(6, output['iterations'])
npt.assert_equal(7, output['funcalls'])
npt.assert_equal(0, output['error_num'])