"""
Ex. 7.1 from "A primer on...
Implement a class F that represents a mathematical function
and supports the use cases given in the exercise text. 
"""

import numpy as np

class F:
    def __init__(self, a, w):
        self.a = a
        self.w = w

    def value(self, x):
        return np.exp(-self.a * x) * np.sin(self.w * x)

f = F(a=1.0, w=0.1)
print(f(x = np.pi))
print(f.value(x = np.pi))
f.a = 2
print(f.value(np.pi))