布林线 (BBANDS)
已核验的 StratForge C++23 API、计算与预热行为。
Route: /indicators/bbands/
固定使用简单移动平均和总体标准差(除以 n,而不是 n - 1)。三条轨道与输入价格单位相同。此构造函数没有 movav 选项。
mid = SMA(period)
top = mid + devfactor * sqrt(sum((price - mid)^2) / period)
bottom = mid - devfactor * sqrt(sum((price - mid)^2) / period)
参数
period = 20devfactor = 2.0
计算示例
period = 4,价格 [2, 4, 6, 8] 的均值为 5,偏差平方为 [9, 1, 1, 9],方差为 5,标准差为 sqrt(5)。devfactor = 2 时:mid = 5,top = 9.472136,bottom = 0.527864(六位小数)。前三根柱输出 NaN,第 4 根首次有效;默认周期需要 20 根柱。
使用有限价格及正数周期和回看长度。此版本把零周期或零回看长度归一为 1,不校验自定义安全值,也不保证非有限价格的输出有意义。示例计算不是交易信号或收益证据。
C++23 API — StratForge
#include <stratforge/indicators/bollinger.hpp>
#include <cassert>
#include <cmath>
#include <iomanip>
#include <iostream>
int main() {
stratforge::Line<double> close;
stratforge::BollingerBands bands(close, 4, 2.0);
assert(bands.minimum_period() == 4);
for (double price : {2.0, 4.0, 6.0, 8.0}) {
close.forward(price);
bands.next();
if (close.size() < 4) {
assert(std::isnan(bands.mid()[0]));
assert(std::isnan(bands.top()[0]));
assert(std::isnan(bands.bottom()[0]));
}
}
assert(std::abs(bands.mid()[0] - 5.0) < 1e-9);
assert(std::abs(bands.top()[0] - 9.472135955) < 1e-9);
assert(std::abs(bands.bottom()[0] - 0.527864045) < 1e-9);
std::cout << std::fixed << std::setprecision(6)
<< bands.mid()[0] << " " << bands.top()[0] << " "
<< bands.bottom()[0] << "\n";
}
复现
StratForge d25404dcf2c3842ba304ddc60ac19cfec1f8aa37 (2026-08-28); GCC 14, C++23; scalar build, no xsimd dependency.
git clone https://github.com/StratCraftsAI/StratForge.git StratForge
git -C StratForge checkout --detach d25404dcf2c3842ba304ddc60ac19cfec1f8aa37
g++-14 -std=c++23 -O2 -Wall -Wextra -pedantic -IStratForge/include example.cpp -o example
./example
example.cpp: C++23 API. stdout:
5.000000 9.472136 0.527864
