使用Python求解五阶多项式

Question

I think it is pretty clear from the title as to what I am trying to accomplish. So, let us get on with the code:

import math

import numpy as np

import scipy

#from scipy import scipy.optimize.fsolve as sci_solve



x0 = -5

def function(x):

    x**5 + x**4 + x**3 + x**2 + x + 1

#print sci_solve(function, x0)

print scipy.optimize.fsolve(function, x0)

Okay, so when I run this code, I get [-5.]. When did it simply print my initial value, and not the roots of this equation? Also, when I ran the code without # before the lines containing the code #from scipy import scipy.optimize.fsolve as sci_solve and print sci_solve(function, x0), it gave me a syntax error.

What am I doing wrong?

As hcwhsa points out, I neglected to relate to the reader the version of python I am using, and I am terribly sorry for this. I am using version 2.7

Answer 1

在问这个问题之前，我从未真正听说过scipy模块（因此感谢您），但是从http://folk.uio.no/inf3330/scripting/doc/python/SciPy/tutorial/给出的示例代码中old / node18.html ，看来您需要在def function(x):之后的多项式之前放一个return语句。

Answer 2

One way to do this:

from scipy import *

x0 = -5
p = poly1d([1, 1, 1, 1, 1, 1])

# evaluate for x = x0
p(x0)

# get roots
roots(p)

This gives you all roots, including complex ones. If you want only real roots, you can iterate over roots(p) (it's an array) and check that each item's imag attribute is 0.0.