Python查找函数f（x）=0根的解决方法

本文实例讲述了Python查找函数f（x）=0根的解决方法。分享给大家供大家参考。具体实现方法如下：

''' root = ridder(f,a,b,tol=1.0e-9).
  Finds a root of f(x) = 0 with Ridder's method.
  The root must be bracketed in (a,b).
'''
import error
from math import sqrt
def ridder(f,a,b,tol=1.0e-9):  
  fa = f(a)
  if fa == 0.0: return a
  fb = f(b)
  if fb == 0.0: return b
  if fa*fb > 0.0: error.err('Root is not bracketed')
  for i in range(30):
   # Compute the improved root x from Ridder's formula
    c = 0.5*(a + b); fc = f(c)
    s = sqrt(fc**2 - fa*fb)
    if s == 0.0: return None
    dx = (c - a)*fc/s
    if (fa - fb)  0:
      if abs(x - xOld)  0.0:
      if fa*fx 

希望本文所述对大家的Python程序设计有所帮助。