本文整理汇总了C++中Bracket::setA方法的典型用法代码示例。如果您正苦于以下问题：C++ Bracket::setA方法的具体用法？C++ Bracket::setA怎么用？C++ Bracket::setA使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类Bracket的用法示例。
在下文中一共展示了Bracket::setA方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的C++代码示例。
示例1: bracketMinimum
Bracket OneDimensionOptimizationTools::bracketMinimum(
double a,
double b,
Function * function,
ParameterList parameters)
{
Bracket bracket;
// Copy the parameter to use.
bracket.a.x = a;
parameters[0].setValue(bracket.a.x);
bracket.a.f = function->f(parameters);
bracket.b.x = b;
parameters[0].setValue(bracket.b.x);
bracket.b.f = function->f(parameters);
if (bracket.b.f > bracket.a.f)
{
// Switch roles of first and second point so that we can go downhill
// in the direction from a to b.
NumTools::swap<double>(bracket.a.x, bracket.b.x);
NumTools::swap<double>(bracket.a.f, bracket.b.f);
}
// First guess for third point:
bracket.c.x = bracket.b.x + NumConstants::GOLDEN_RATIO_PHI() * (bracket.b.x - bracket.a.x);
parameters[0].setValue(bracket.c.x);
bracket.c.f = function->f(parameters);
// Keep returning here until we bracket:
while (bracket.b.f > bracket.c.f)
{
// Compute xu by parabolic extrapolation from a, b, c. TINY is used to prevent
// any possible division by 0.
double r = (bracket.b.x - bracket.a.x) * (bracket.b.f - bracket.c.f);
double q = (bracket.b.x - bracket.c.x) * (bracket.b.f - bracket.a.f);
double xu = bracket.b.x - ((bracket.b.x - bracket.c.x) * q - (bracket.b.x - bracket.a.x) * r) /
(2.0 * NumTools::sign(NumTools::max(NumTools::abs(q - r), NumConstants::VERY_TINY()), q - r));
double xulim = (bracket.b.x) + GLIMIT * (bracket.c.x - bracket.b.x);
double fu;
// We don't go farther than this.
// Test various possibilities:
if ((bracket.b.x - xu) * (xu - bracket.c.x) > 0.0)
{
parameters[0].setValue(xu);
fu = function->f(parameters);
if (fu < bracket.c.f)
{
bracket.setA(bracket.b.x, bracket.b.f);
bracket.setB(xu, fu);
return bracket;
}
else if (fu > bracket.b.f)
{
bracket.setC(xu, fu);
return bracket;
}
// Parabolic fit was no use.
// Use default magnification.
xu = bracket.c.x + NumConstants::GOLDEN_RATIO_PHI() * (bracket.c.x - bracket.b.x);
parameters[0].setValue(xu);
fu = function->f(parameters);
}
else if ((bracket.c.x - xu) * (xu - xulim) > 0.0)
{
// Parabolic fit is between point 3 and its allowed limit.
parameters[0].setValue(xu);
fu = function->f(parameters);
if (fu < bracket.c.f)
{
NumTools::shift<double>(bracket.b.x, bracket.c.x, xu, bracket.c.x + NumConstants::GOLDEN_RATIO_PHI() * (bracket.c.x - bracket.b.x));
parameters[0].setValue(xu);
NumTools::shift<double>(bracket.b.f, bracket.c.f, fu, function->f(parameters));
}
}
else if ((xu - xulim) * (xulim - bracket.c.x) >= 0.0)
{
// Limit parabolic xu to maximum allowed value.
xu = xulim;
parameters[0].setValue(xu);
fu = function->f(parameters);
}
else
{
// Reject parabolic xu, use default magnification.
xu = bracket.c.x + NumConstants::GOLDEN_RATIO_PHI() * (bracket.c.x - bracket.b.x);
parameters[0].setValue(xu);
fu = function->f(parameters);
}
// Eliminate oldest point and continue.
NumTools::shift<double>(bracket.a.x, bracket.b.x, bracket.c.x, xu);
NumTools::shift<double>(bracket.a.f, bracket.b.f, bracket.c.f, fu);
}
return bracket;
}