已知截止频率Pf，增益Gain，增益因子Q，利用Qt qcustomplot库分别画出LowShelf滤波和HighShelf在20Hz到20kHz区间范围内的频响曲线

好的，我会给出利用Qt qcustomplot库分别画出LowShelf滤波和HighShelf在20Hz到20kHz区间范围内的频响曲线的代码。

首先，我们需要导入qcustomplot库并创建一个QCustomPlot对象。然后，我们需要设置坐标轴的范围和标签。以下是创建坐标轴的代码：

// 创建QCustomPlot对象
QCustomPlot *customPlot = new QCustomPlot(this);
customPlot->setGeometry(10, 10, 500, 300);

// 创建对数坐标轴
customPlot->xAxis->setScaleType(QCPAxis::stLogarithmic);
customPlot->yAxis->setScaleType(QCPAxis::stLogarithmic);
customPlot->xAxis->setRange(20, 20000);
customPlot->yAxis->setRange(-40, 20);
customPlot->xAxis->setLabel("Frequency (Hz)");
customPlot->yAxis->setLabel("Gain (dB)");

接下来，我们需要计算LowShelf滤波器和HighShelf滤波器的频响曲线。以下是计算频响曲线的代码：

// 计算LowShelf滤波器频响曲线
QVector<double> xLow, yLow;
for (double i = 20; i <= 20000; i *= 1.01) {
    double gainLow = 10 * log10(qPow(Q, 2)/((qPow(i, 2)/qPow(Pf, 2)) + 1 - (i/Pf) * Q));
    double gainLowShelf = Gain + gainLow;
    xLow.append(i);
    yLow.append(gainLowShelf);
}

// 计算HighShelf滤波器频响曲线
QVector<double> xHigh, yHigh;
for (double i = 20; i <= 20000; i *= 1.01) {
    double gainHigh = 10 * log10(qPow(i, 2)/((qPow(Pf, 2))/qPow(Q, 2) + (i/Pf) * Q + 1));
    double gainHighShelf = Gain + gainHigh;
    xHigh.append(i);
    yHigh.append(gainHighShelf);
}

最后，我们可以使用addGraph()函数将LowShelf滤波器和HighShelf滤波器的频响曲线绘制到qcustomplot上。以下是完整的代码示例：

// 创建QCustomPlot对象
QCustomPlot *customPlot = new QCustomPlot(this);
customPlot->setGeometry(10, 10, 500, 300);

// 创建对数坐标轴
customPlot->xAxis->setScaleType(QCPAxis::stLogarithmic);
customPlot->yAxis->setScaleType(QCPAxis::stLogarithmic);
customPlot->xAxis->setRange(20, 20000);
customPlot->yAxis->setRange(-40, 20);
customPlot->xAxis->setLabel("Frequency (Hz)");
customPlot->yAxis->setLabel("Gain (dB)");

// 计算LowShelf滤波器频响曲线
QVector<double> xLow, yLow;
for (double i = 20; i <= 20000; i *= 1.01) {
    double gainLow = 10 * log10(qPow(Q, 2)/((qPow(i, 2)/qPow(Pf, 2)) + 1 - (i/Pf) * Q));
    double gainLowShelf = Gain + gainLow;
    xLow.append(i);
    yLow.append(gainLowShelf);
}

// 计算HighShelf滤波器频响曲线
QVector<double> xHigh, yHigh;
for (double i = 20; i <= 20000; i *= 1.01) {
    double gainHigh = 10 * log10(qPow(i, 2)/((qPow(Pf, 2))/qPow(Q, 2) + (i/Pf) * Q + 1));
    double gainHighShelf = Gain + gainHigh;
    xHigh.append(i);
    yHigh.append(gainHighShelf);
}

// 绘制频响曲线
customPlot->addGraph();
customPlot->graph(0)->setData(xLow, yLow);
customPlot->graph(0)->setPen(QPen(Qt::blue));
customPlot->addGraph();
customPlot->graph(1)->setData(xHigh, yHigh);
customPlot->graph(1)->setPen(QPen(Qt::red));
customPlot->replot();

这样，我们就可以在20Hz到20kHz区间范围内绘制出LowShelf滤波器和HighShelf滤波器的频响曲线了。