import numpy as np


#P145 例題2
x=np.array([-1,-0.75,-0.5,-0.25,0,0.25,0.5,0.75,1])
y=np.array([-0.2209,0.3295,0.8826,1.4392,2.0003,2.5645,3.1334,3.7601,4.2836])

#習題六 2
x=np.array([1,3,4,5,6,7,8,9,10])
y=np.array([10,5,4,2,1,1,2,3,4])

#習題六 4
x=np.array([19,25,31,38,44])
y=np.array([19.0,32.3,49.0,73.3,97.8])

print
 
(len(x))
#print(np.sum(x))
print(np.sum(x**2))
#print(np.sum(x**3))
print(np.sum(x**4))

print(np.sum(y))
#print(np.sum(x*y))
print(np.sum((x**2)*y))

# a=([len(x),np.sum(x),np.sum(x**2)],
#     [np.sum(x),np.sum(x**2),np.sum(x**3)],
#     [np.sum(x**2),np.sum(x**3),np.sum(x**4)])
# b=(np.sum(y),np.sum(x*y),np.sum((x**2)*y))
 


a=([len(x),np.sum(x**2)],
    [np.sum(x**2),np.sum(x**4)])
b=(np.sum(y),np.sum((x**2)*y))

x=np.linalg.solve(a,b)
print(x)