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heaviside_fitting.py
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Fri, Nov 1, 06:42

heaviside_fitting.py
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# Copyright (C) 2018 by the RROMPy authors
#
# This file is part of RROMPy.
#
# RROMPy is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# RROMPy is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with RROMPy. If not, see <http://www.gnu.org/licenses/>.
#
import numpy as np
from rrompy.utilities.poly_fitting.heaviside import (polybases, polyfitname,
polydomcoeff,
heaviside2rational,
rational2heaviside)
from rrompy.utilities.poly_fitting.polynomial.polynomial_interpolator import (
PolynomialInterpolator, PolynomialInterpolatorNodal)
def test_monomial_heaviside():
polyhsname = "MONOMIAL_HEAVISIDE"
assert polyhsname in polybases
fitname = polyfitname(polyhsname)
domcoeff = polydomcoeff(5, polyhsname)
assert fitname == "polyfit_heaviside"
assert np.isclose(domcoeff, 1., rtol = 1e-5)
pls = np.array([-5., 0., 2.])
cHS = np.array([4., 1., -10., -25., 4., .25])
cNum = np.array([-10., 195., -120., -15.5, 4.75, .25])
cDen = np.array([0., -10., 3., 1.])
cNum /= np.linalg.norm(cDen)
cDen /= np.linalg.norm(cDen)
numI = PolynomialInterpolator()
numI.coeffs, numI.npar, numI.polybasis = cNum, 1, "MONOMIAL"
denI = PolynomialInterpolator()
denI.coeffs, denI.npar, denI.polybasis = cDen, 1, "MONOMIAL"
numA, denA = heaviside2rational(cHS, pls, [-10., 10.])
assert isinstance(denA, PolynomialInterpolatorNodal)
cA, plsA, _ = rational2heaviside(numI, denI, [-10., 10.])
numA.coeffs /= (denA.coeffs[1] / cDen[1])
denA.coeffs /= (denA.coeffs[1] / cDen[1])
assert np.allclose(numA.coeffs, numI.coeffs, atol = 1e-5)
assert np.allclose(denA.coeffs, denI.coeffs, atol = 1e-5)
assert np.allclose(cA, cHS, atol = 1e-5)
assert np.allclose(plsA, pls, atol = 1e-5)
def test_chebyshev_heaviside():
polyhsname = "CHEBYSHEV_HEAVISIDE"
assert polyhsname in polybases
fitname = polyfitname(polyhsname)
domcoeff = polydomcoeff(5, polyhsname)
assert fitname == "chebfit_heaviside"
assert np.isclose(domcoeff, 16, rtol = 1e-5)
pls = np.array([-5., 0., 2. + 1.j, 7])
cHS = np.array([4., 1., 25., -10., -25., 4., .25], dtype = np.complex)
numA, denA = heaviside2rational(cHS, pls, [-10., 10.])
cA, plsA, _ = rational2heaviside(numA, denA, [-10., 10.])
assert np.allclose(cA, cHS, atol = 1e-5)
assert np.allclose(plsA, pls, atol = 1e-5)

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