• 欢迎访问开心洋葱网站,在线教程,推荐使用最新版火狐浏览器和Chrome浏览器访问本网站,欢迎加入开心洋葱 QQ群
  • 为方便开心洋葱网用户,开心洋葱官网已经开启复制功能!
  • 欢迎访问开心洋葱网站,手机也能访问哦~欢迎加入开心洋葱多维思维学习平台 QQ群
  • 如果您觉得本站非常有看点,那么赶紧使用Ctrl+D 收藏开心洋葱吧~~~~~~~~~~~~~!
  • 由于近期流量激增,小站的ECS没能经的起亲们的访问,本站依然没有盈利,如果各位看如果觉着文字不错,还请看官给小站打个赏~~~~~~~~~~~~~!

Powell’s method of minimizing user-supplied function in Python

python 水墨上仙 1783次浏览

Powell’s method of minimizing user-supplied function in Python

''' xMin,nCyc = powell(F,x,h=0.1,tol=1.0e-6)
    Powell's method of minimizing user-supplied function F(x).
    x    = starting point
    h   = initial search increment used in 'bracket'
    xMin = mimimum point
    nCyc = number of cycles
'''
from numpy import identity,array,dot,zeros,argmax
from goldSearch import *
from math import sqrt
 
def powell(F,x,h=0.1,tol=1.0e-6):
 
    def f(s): return F(x + s*v)    # F in direction of v
 
    n = len(x)                     # Number of design variables
    df = zeros(n)                  # Decreases of F stored here
    u = identity(n)                # Vectors v stored here by rows
    for j in range(30):            # Allow for 30 cycles:
        xOld = x.copy()            # Save starting point
        fOld = F(xOld)
      # First n line searches record decreases of F
        for i in range(n):
            v = u[i]
            a,b = bracket(f,0.0,h)
            s,fMin = search(f,a,b)
            df[i] = fOld - fMin
            fOld = fMin
            x = x + s*v
      # Last line search in the cycle    
        v = x - xOld
        a,b = bracket(f,0.0,h)
        s,fLast = search(f,a,b)
        x = x + s*v
      # Check for convergence
        if sqrt(dot(x-xOld,x-xOld)/n) < tol: return x,j+1
      # Identify biggest decrease & update search directions
        iMax = argmax(df)
        for i in range(iMax,n-1):
            u[i] = u[i+1]
        u[n-1] = v
    print "Powell did not converge"


开心洋葱 , 版权所有丨如未注明 , 均为原创丨未经授权请勿修改 , 转载请注明Powell’s method of minimizing user-supplied function in Python
喜欢 (0)
加载中……