简单的范德蒙矩阵与for循环

Question

This is a very simple question.My aim is to eventually create a Vandermonde matrix but first i need to:

Write a function that takes a real number α and an integer n as input, and returns a vector v=(1,α,α2,…,αn−1)

so far i have:

import numpy as np

n =6
a= 3
for i in range(n):
    v = np.array([1, a**2, a**(n-1)])
print v

I get: [ 1 9 243] which is not what i want. Please can you help, thank you!

Answer 1

Use a list comprehension :

v = np.array([a**x for x in range(n)])

This is equivalent to:

v = []
for x in range(n):
    v.append(a**x)
v = np.array(v)