发布于 2015-10-05 23:58:47 | 175 次阅读 | 评论: 0 | 来源: 网友投递
这里有新鲜出炉的Python3 官方中文指南，程序狗速度看过来！
Python编程语言
Python 是一种面向对象、解释型计算机程序设计语言，由Guido van Rossum于1989年底发明，第一个公开发行版发行于1991年。Python语法简洁而清晰，具有丰富和强大的类库。它常被昵称为胶水语言，它能够把用其他语言制作的各种模块（尤其是C/C++）很轻松地联结在一起。
本文实例讲述了python中黄金分割法实现方法。分享给大家供大家参考。具体实现方法如下：
''' a,b = bracket(f,xStart,h)
Finds the brackets (a,b) of a minimum point of the
user-supplied scalar function f(x).
The search starts downhill from xStart with a step
length h.
x,fMin = search(f,a,b,tol=1.0e-6)
Golden section method for determining x that minimizes
the user-supplied scalar function f(x).
The minimum must be bracketed in (a,b).
'''
from math import log, ceil
def bracket(f,x1,h):
c = 1.618033989
f1 = f(x1)
x2 = x1 + h; f2 = f(x2)
# Determine downhill direction and change sign of h if needed
if f2 > f1:
h = -h
x2 = x1 + h; f2 = f(x2)
# Check if minimum between x1 - h and x1 + h
if f2 > f1: return x2,x1 - h
# Search loop
for i in range (100):
h = c*h
x3 = x2 + h; f3 = f(x3)
if f3 > f2: return x1,x3
x1 = x2; x2 = x3
f1 = f2; f2 = f3
print "Bracket did not find a mimimum"
def search(f,a,b,tol=1.0e-9):
nIter = int(ceil(-2.078087*log(tol/abs(b-a)))) # Eq. (10.4)
R = 0.618033989
C = 1.0 - R
# First telescoping
x1 = R*a + C*b; x2 = C*a + R*b
f1 = f(x1); f2 = f(x2)
# Main loop
for i in range(nIter):
if f1 > f2:
a = x1
x1 = x2; f1 = f2
x2 = C*a + R*b; f2 = f(x2)
else:
b = x2
x2 = x1; f2 = f1
x1 = R*a + C*b; f1 = f(x1)
if f1 < f2: return x1,f1
else: return x2,f2