taylorwin(L,nbar,sll)加窗函数 C/C++实现

这里给出一个使用汉宁窗函数的例子：

#include <math.h>

void taylorwin(double* w, int n, double nbar, double sll) {
    double alpha = pow(10, -sll/20);
    double A = -20*log10(alpha);
    double M = ceil((n-1)/2.0);
    for (int i = 0; i < n; i++) {
        double t = i - M;
        double p = t/M;
        double w_han = 0.5 + 0.5*cos(2*M_PI*t/n);
        double w_taylor = 0;
        for (int k = 0; k <= nbar; k++) {
            double a_k = 2/(nbar+1)*sin((nbar+1)/2.0*M_PI*(p+k/nbar));
            double w_k = 1;
            for (int j = 1; j <= M; j++) {
                w_k *= (1 - a_k*a_k)/(1 - 2*a_k*cos(2*M_PI*j/n) + a_k*a_k);
            }
            w_taylor += pow(-1, k)*w_k*a_k;
        }
        w[i] = w_han*w_taylor;
    }
}

其中，`w`是窗函数数组，`n`是窗函数长度，`nbar`是窗函数的参数，`sll`是副瓣抑制水平。具体的计算方法可以参考文献：

[1] Harris, Fredric J. "On the use of windows for harmonic analysis with the discrete fourier transform." Proceedings of the IEEE 66.1 (1978): 51-83.

[2] Nuttall, Albert H. "Some windows with very good sidelobe behavior." Acoustics, Speech and Signal Processing, IEEE Transactions on 29.1 (1981): 84-91.