From 98a32391be03095a2d9cc7c9cc89662275bbd8ee Mon Sep 17 00:00:00 2001
From: Zhuoran Han <zhuoranh@mit.edu>
Date: Fri, 17 Aug 2018 15:00:39 -0500
Subject: [PATCH] Change Polynomial class and fix PEP 8 style

---
 openmc/__init__.py   |  2 +-
 openmc/polynomial.py | 71 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)
 create mode 100644 openmc/polynomial.py

diff --git a/openmc/__init__.py b/openmc/__init__.py
index c7db3171c..4627c340b 100644
--- a/openmc/__init__.py
+++ b/openmc/__init__.py
@@ -28,7 +28,7 @@ from openmc.particle_restart import *
 from openmc.mixin import *
 from openmc.plotter import *
 from openmc.search import *
-from openmc.polynomials import *
+from openmc.polynomial import *
 from . import examples
 
 # Import a few convencience functions that used to be here
diff --git a/openmc/polynomial.py b/openmc/polynomial.py
new file mode 100644
index 000000000..fce068f18
--- /dev/null
+++ b/openmc/polynomial.py
@@ -0,0 +1,71 @@
+import numpy as np
+import openmc
+import openmc.capi as capi
+
+
+def legendre_from_expcoef(coef, domain):
+    """Download file from a URL
+
+    Parameters
+    ----------
+    coef : Iterable of float
+        A list of coefficients of each term in Legendre polynomials
+
+    Returns
+    -------
+    Legendre class
+        A numpy Legendre series object
+
+    """
+    n = np.arange(len(coef) + 1)
+    c = (2*n + 1) * np.asarray(coef) / (domain[1] - domain[0])
+    return np.polynomial.Legendre(c, domain)
+
+
+class Polynomial(object):
+    """Abstract Polynomial Class for creating polynomials.
+    """
+    def __init__(self, coef):
+        self.coef = np.asarray(coef)
+
+
+class ZernikeRadial(Polynomial):
+    """Create radial only Zernike polynomials given coefficients and domian.
+
+    The radial only Zernike polynomials are defined as in
+    :class:`ZernikeRadialFilter`.
+
+    Parameters
+    ----------
+    coef : Iterable of float
+        A list of coefficients of each term in radial only Zernike polynomials
+    radius : float
+        Domain of Zernike polynomials to be applied on. Default is 1.
+    r : float
+        Position to be evaluated, normalized on radius [0,1]
+
+    Attributes
+    ----------
+    order : int
+        The maximum (even) order of Zernike polynomials.
+    radius : float
+        Domain of Zernike polynomials to be applied on. Default is 1.
+    norm_coef : iterable of float
+        The list of coefficients of each term in the polynomials after
+        normailization.
+
+    """
+    def __init__(self, coef, radius=1):
+        super().__init__(coef)
+        self._order = 2 * (self.n_coef - 1)
+        self.radius = radius
+        norm_vec = (2 * np.arange(self.n_coef) + 1) / (np.pi * radius**2)
+        self._norm_coef = norm_vec * self.coef
+
+    @property
+    def order(self):
+        return self._order
+
+    def __call__(self, r):
+        zn_rad = capi.calc_zn_rad(self.order, r)
+        return np.sum(self._norm_coef * zn_rad)