qt c++拟合直线

在Qt C++中拟合直线可以使用最小二乘法，以下是一个简单的拟合直线的示例代码：

#include <QCoreApplication>
#include <QtMath>
#include <QDebug>

double fitLine(const QVector<double>& xData, const QVector<double>& yData, double& slope, double& yIntercept)
{
    double xSum = 0, ySum = 0, xySum = 0, xSquaredSum = 0;
    int n = xData.size();

    for(int i=0; i<n; i++)
    {
        xSum += xData[i];
        ySum += yData[i];
        xySum += xData[i] * yData[i];
        xSquaredSum += xData[i] * xData[i];
    }

    double denominator = n * xSquaredSum - qPow(xSum, 2);
    if(denominator == 0)
        return 0;

    slope = (n * xySum - xSum * ySum) / denominator;
    yIntercept = (ySum * xSquaredSum - xSum * xySum) / denominator;

    // calculate r-squared
    double yMean = ySum / n;
    double ssTotal = 0, ssResidual = 0;
    for(int i=0; i<n; i++)
    {
        ssTotal += qPow(yData[i] - yMean, 2);
        ssResidual += qPow(yData[i] - yIntercept, 2);
    }

    return 1 - (ssResidual / ssTotal);
}

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QVector<double> xData{1, 2, 3, 4, 5};
    QVector<double> yData{2.1, 3.9, 6.1, 8.2, 9.8};

    double slope = 0, yIntercept = 0;
    double rSquared = fitLine(xData, yData, slope, yIntercept);

    qDebug() << "Slope:" << slope << ", Y Intercept:" << yIntercept << ", R-Squared:" << rSquared;

    return a.exec();
}

其中`xData`和`yData`分别是x和y轴数据点的向量，`slope`和`yIntercept`是拟合出的直线的斜率和截距。`fitLine`函数返回的是R平方值，用于衡量模型的拟合程度。