x
Yes
No
Do you want to visit DriveHQ English website?
首页
产品服务
价格
免费试用
下载客户端
关于我们
云文件服务
|
云备份服务
|
FTP服务
|
企业邮箱服务
|
网站托管
|
客户端软件
云文件服务
云备份服务
FTP服务
企业级邮箱服务
网站托管
客户端软件
minima.hpp - Hosted on DriveHQ Cloud IT Platform
返回上层目录
上传
下载
共享
发布
新建文件夹
新建文件
复制
剪切
删除
粘贴
评论
升级服务
路径: \\game3dprogramming\materials\GameFactory\GameFactoryDemo\references\boost_1_35_0\boost\math\tools\minima.hpp
旋转
特效
属性
历史版本
// (C) Copyright John Maddock 2006. // Use, modification and distribution are subject to the // Boost Software License, Version 1.0. (See accompanying file // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) #ifndef BOOST_MATH_TOOLS_MINIMA_HPP #define BOOST_MATH_TOOLS_MINIMA_HPP #include
#include
#include
#include
#include
namespace boost{ namespace math{ namespace tools{ template
std::pair
brent_find_minima(F f, T min, T max, int bits, boost::uintmax_t& max_iter) { BOOST_MATH_STD_USING bits = (std::min)(policies::digits
>() / 2, bits); T tolerance = static_cast
(ldexp(1.0, 1-bits)); T x; // minima so far T w; // second best point T v; // previous value of w T u; // most recent evaluation point T delta; // The distance moved in the last step T delta2; // The distance moved in the step before last T fu, fv, fw, fx; // function evaluations at u, v, w, x T mid; // midpoint of min and max T fract1, fract2; // minimal relative movement in x static const T golden = 0.3819660f; // golden ratio, don't need too much precision here! x = w = v = max; fw = fv = fx = f(x); delta2 = delta = 0; uintmax_t count = max_iter; do{ // get midpoint mid = (min + max) / 2; // work out if we're done already: fract1 = tolerance * fabs(x) + tolerance / 4; fract2 = 2 * fract1; if(fabs(x - mid) <= (fract2 - (max - min) / 2)) break; if(fabs(delta2) > fract1) { // try and construct a parabolic fit: T r = (x - w) * (fx - fv); T q = (x - v) * (fx - fw); T p = (x - v) * q - (x - w) * r; q = 2 * (q - r); if(q > 0) p = -p; q = fabs(q); T td = delta2; delta2 = delta; // determine whether a parabolic step is acceptible or not: if((fabs(p) >= fabs(q * td / 2)) || (p <= q * (min - x)) || (p >= q * (max - x))) { // nope, try golden section instead delta2 = (x >= mid) ? min - x : max - x; delta = golden * delta2; } else { // whew, parabolic fit: delta = p / q; u = x + delta; if(((u - min) < fract2) || ((max- u) < fract2)) delta = (mid - x) < 0 ? -fabs(fract1) : fabs(fract1); } } else { // golden section: delta2 = (x >= mid) ? min - x : max - x; delta = golden * delta2; } // update current position: u = (fabs(delta) >= fract1) ? x + delta : (delta > 0 ? x + fabs(fract1) : x - fabs(fract1)); fu = f(u); if(fu <= fx) { // good new point is an improvement! // update brackets: if(u >= x) min = x; else max = x; // update control points: v = w; w = x; x = u; fv = fw; fw = fx; fx = fu; } else { // Oh dear, point u is worse than what we have already, // even so it *must* be better than one of our endpoints: if(u < x) min = u; else max = u; if((fu <= fw) || (w == x)) { // however it is at least second best: v = w; w = u; fv = fw; fw = fu; } else if((fu <= fv) || (v == x) || (v == w)) { // third best: v = u; fv = fu; } } }while(--count); max_iter -= count; return std::make_pair(x, fx); } template
inline std::pair
brent_find_minima(F f, T min, T max, int digits) { boost::uintmax_t m = (std::numeric_limits
::max)(); return brent_find_minima(f, min, max, digits, m); } }}} // namespaces #endif
minima.hpp
网页地址
文件地址
上一页
3/19
下一页
下载
( 4 KB )
Comments
Total ratings:
0
Average rating:
无评论
of 10
Would you like to comment?
Join now
, or
Logon
if you are already a member.