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""" |
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A sub-package for efficiently dealing with polynomials. |
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Within the documentation for this sub-package, a "finite power series," |
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i.e., a polynomial (also referred to simply as a "series") is represented |
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by a 1-D numpy array of the polynomial's coefficients, ordered from lowest |
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order term to highest. For example, array([1,2,3]) represents |
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``P_0 + 2*P_1 + 3*P_2``, where P_n is the n-th order basis polynomial |
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applicable to the specific module in question, e.g., `polynomial` (which |
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"wraps" the "standard" basis) or `chebyshev`. For optimal performance, |
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all operations on polynomials, including evaluation at an argument, are |
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implemented as operations on the coefficients. Additional (module-specific) |
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information can be found in the docstring for the module of interest. |
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This package provides *convenience classes* for each of six different kinds |
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of polynomials: |
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======================== ================ |
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**Name** **Provides** |
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======================== ================ |
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`~polynomial.Polynomial` Power series |
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`~chebyshev.Chebyshev` Chebyshev series |
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`~legendre.Legendre` Legendre series |
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`~laguerre.Laguerre` Laguerre series |
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`~hermite.Hermite` Hermite series |
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`~hermite_e.HermiteE` HermiteE series |
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======================== ================ |
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These *convenience classes* provide a consistent interface for creating, |
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manipulating, and fitting data with polynomials of different bases. |
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The convenience classes are the preferred interface for the `~numpy.polynomial` |
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package, and are available from the ``numpy.polynomial`` namespace. |
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This eliminates the need to navigate to the corresponding submodules, e.g. |
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``np.polynomial.Polynomial`` or ``np.polynomial.Chebyshev`` instead of |
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``np.polynomial.polynomial.Polynomial`` or |
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``np.polynomial.chebyshev.Chebyshev``, respectively. |
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The classes provide a more consistent and concise interface than the |
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type-specific functions defined in the submodules for each type of polynomial. |
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For example, to fit a Chebyshev polynomial with degree ``1`` to data given |
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by arrays ``xdata`` and ``ydata``, the |
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`~chebyshev.Chebyshev.fit` class method:: |
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>>> from numpy.polynomial import Chebyshev |
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>>> xdata = [1, 2, 3, 4] |
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>>> ydata = [1, 4, 9, 16] |
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>>> c = Chebyshev.fit(xdata, ydata, deg=1) |
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is preferred over the `chebyshev.chebfit` function from the |
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``np.polynomial.chebyshev`` module:: |
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>>> from numpy.polynomial.chebyshev import chebfit |
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>>> c = chebfit(xdata, ydata, deg=1) |
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See :doc:`routines.polynomials.classes` for more details. |
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Convenience Classes |
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=================== |
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The following lists the various constants and methods common to all of |
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the classes representing the various kinds of polynomials. In the following, |
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the term ``Poly`` represents any one of the convenience classes (e.g. |
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`~polynomial.Polynomial`, `~chebyshev.Chebyshev`, `~hermite.Hermite`, etc.) |
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while the lowercase ``p`` represents an **instance** of a polynomial class. |
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Constants |
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--------- |
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- ``Poly.domain`` -- Default domain |
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- ``Poly.window`` -- Default window |
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- ``Poly.basis_name`` -- String used to represent the basis |
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- ``Poly.maxpower`` -- Maximum value ``n`` such that ``p**n`` is allowed |
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- ``Poly.nickname`` -- String used in printing |
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Creation |
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-------- |
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Methods for creating polynomial instances. |
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- ``Poly.basis(degree)`` -- Basis polynomial of given degree |
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- ``Poly.identity()`` -- ``p`` where ``p(x) = x`` for all ``x`` |
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- ``Poly.fit(x, y, deg)`` -- ``p`` of degree ``deg`` with coefficients |
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determined by the least-squares fit to the data ``x``, ``y`` |
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- ``Poly.fromroots(roots)`` -- ``p`` with specified roots |
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- ``p.copy()`` -- Create a copy of ``p`` |
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Conversion |
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---------- |
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Methods for converting a polynomial instance of one kind to another. |
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- ``p.cast(Poly)`` -- Convert ``p`` to instance of kind ``Poly`` |
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- ``p.convert(Poly)`` -- Convert ``p`` to instance of kind ``Poly`` or map |
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between ``domain`` and ``window`` |
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Calculus |
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-------- |
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- ``p.deriv()`` -- Take the derivative of ``p`` |
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- ``p.integ()`` -- Integrate ``p`` |
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Validation |
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---------- |
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- ``Poly.has_samecoef(p1, p2)`` -- Check if coefficients match |
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- ``Poly.has_samedomain(p1, p2)`` -- Check if domains match |
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- ``Poly.has_sametype(p1, p2)`` -- Check if types match |
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- ``Poly.has_samewindow(p1, p2)`` -- Check if windows match |
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Misc |
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---- |
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- ``p.linspace()`` -- Return ``x, p(x)`` at equally-spaced points in ``domain`` |
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- ``p.mapparms()`` -- Return the parameters for the linear mapping between |
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``domain`` and ``window``. |
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- ``p.roots()`` -- Return the roots of ``p``. |
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- ``p.trim()`` -- Remove trailing coefficients. |
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- ``p.cutdeg(degree)`` -- Truncate ``p`` to given degree |
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- ``p.truncate(size)`` -- Truncate ``p`` to given size |
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""" |
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from .polynomial import Polynomial |
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from .chebyshev import Chebyshev |
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from .legendre import Legendre |
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from .hermite import Hermite |
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from .hermite_e import HermiteE |
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from .laguerre import Laguerre |
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__all__ = [ |
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"set_default_printstyle", |
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"polynomial", "Polynomial", |
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"chebyshev", "Chebyshev", |
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"legendre", "Legendre", |
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"hermite", "Hermite", |
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"hermite_e", "HermiteE", |
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"laguerre", "Laguerre", |
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] |
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def set_default_printstyle(style): |
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""" |
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Set the default format for the string representation of polynomials. |
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Values for ``style`` must be valid inputs to ``__format__``, i.e. 'ascii' |
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or 'unicode'. |
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Parameters |
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---------- |
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style : str |
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Format string for default printing style. Must be either 'ascii' or |
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'unicode'. |
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Notes |
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----- |
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The default format depends on the platform: 'unicode' is used on |
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Unix-based systems and 'ascii' on Windows. This determination is based on |
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default font support for the unicode superscript and subscript ranges. |
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Examples |
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-------- |
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>>> p = np.polynomial.Polynomial([1, 2, 3]) |
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>>> c = np.polynomial.Chebyshev([1, 2, 3]) |
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>>> np.polynomial.set_default_printstyle('unicode') |
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>>> print(p) |
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1.0 + 2.0·x + 3.0·x² |
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>>> print(c) |
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1.0 + 2.0·T₁(x) + 3.0·T₂(x) |
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>>> np.polynomial.set_default_printstyle('ascii') |
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>>> print(p) |
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1.0 + 2.0 x + 3.0 x**2 |
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>>> print(c) |
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1.0 + 2.0 T_1(x) + 3.0 T_2(x) |
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>>> # Formatting supersedes all class/package-level defaults |
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>>> print(f"{p:unicode}") |
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1.0 + 2.0·x + 3.0·x² |
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""" |
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if style not in ('unicode', 'ascii'): |
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raise ValueError( |
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f"Unsupported format string '{style}'. Valid options are 'ascii' " |
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f"and 'unicode'" |
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) |
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_use_unicode = True |
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if style == 'ascii': |
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_use_unicode = False |
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from ._polybase import ABCPolyBase |
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ABCPolyBase._use_unicode = _use_unicode |
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from numpy._pytesttester import PytestTester |
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test = PytestTester(__name__) |
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del PytestTester |
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