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""" function.py
Module containing classes representing piece-wise constant and piece-wise linear
functions.
Copyright 2014, Mario Mulansky <mario.mulansky@gmx.net>
"""
from __future__ import print_function
import numpy as np
class PieceWiseConstFunc:
""" A class representing a piece-wise constant function. """
def __init__(self, x, y):
""" Constructs the piece-wise const function.
Params:
- x: array of length N+1 defining the edges of the intervals of the pwc
function.
- y: array of length N defining the function values at the intervals.
"""
self.x = x
self.y = y
def get_plottable_data(self):
""" Returns two arrays containing x- and y-coordinates for immeditate
plotting of the piece-wise function.
"""
x_plot = np.empty(2*len(self.x)-2)
x_plot[0] = self.x[0]
x_plot[1::2] = self.x[1:]
x_plot[2::2] = self.x[1:-1]
y_plot = np.empty(2*len(self.y))
y_plot[::2] = self.y
y_plot[1::2] = self.y
return x_plot, y_plot
def avrg(self):
""" Computes the average of the piece-wise const function:
a = 1/T int f(x) dx where T is the length of the interval.
Returns:
- the average a.
"""
print(self.x)
print(self.y)
return np.sum((self.x[1:]-self.x[:-1]) * self.y) / \
(self.x[-1]-self.x[0])
def abs_avrg(self):
""" Computes the average of the abs value of the piece-wise const
function:
a = 1/T int |f(x)| dx where T is the length of the interval.
Returns:
- the average a.
"""
return np.sum((self.x[1:]-self.x[:-1]) * np.abs(self.y)) / \
(self.x[-1]-self.x[0])
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