写一个切尔雪夫滤波器的c语言代码

以下是一个简单的切尔雪夫滤波器的C语言代码实现：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#define ORDER 4    // 滤波器的阶数

void chebyshev_filter(float *x, float *y, int n, float *a, float *b, int order, float rp, float rs, float wp, float ws);
float chebyshev_gain(float rp, float rs, float wp, float ws);
void chebyshev_coef(float *a, float *b, int order, float gain);

int main() {
    float x[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};    // 输入信号
    float y[10];    // 输出信号
    float a[ORDER + 1];    // 分子系数
    float b[ORDER + 1];    // 分母系数
    float rp = 1.0;    // 通带最大衰减
    float rs = 50.0;   // 阻带最小衰减
    float wp = 0.2;    // 通带截止频率
    float ws = 0.3;    // 阻带截止频率

    chebyshev_coef(a, b, ORDER, chebyshev_gain(rp, rs, wp, ws));
    chebyshev_filter(x, y, 10, a, b, ORDER, rp, rs, wp, ws);

    // 输出结果
    printf("Input signal: ");
    for(int i = 0; i < 10; i++) {
        printf("%f ", x[i]);
    }
    printf("\n");

    printf("Output signal: ");
    for(int i = 0; i < 10; i++) {
        printf("%f ", y[i]);
    }
    printf("\n");

    return 0;
}

// 计算切比雪夫滤波器的增益
float chebyshev_gain(float rp, float rs, float wp, float ws){
    float eps = sqrt(pow(10, 0.1 * rs) - 1);
    float omega_p = wp / 2.0;
    float omega_s = ws / 2.0;
    float omega_c = sqrt(omega_p * omega_s);
    float delta_omega = omega_s - omega_p;
    float a = pow(10, rp / 20.0);
    float b = pow(eps, 2);
    float c = sqrt(a * a - 1);
    float d = sqrt(b + c * c);
    float e = delta_omega / omega_c;
    float f = asinh(1.0 / eps) / order;
    float g = sinh(f * log(e));
    float gain = 1.0 / (sqrt(1.0 + b) * g);
    return gain;
}

// 计算切比雪夫滤波器的系数
void chebyshev_coef(float *a, float *b, int order, float gain){
    // 分别计算分子、分母系数
    for(int i = 0; i <= order; i++) {
        a[i] = 0.0;
        b[i] = 0.0;
        for(int j = 0; j <= order; j++) {
            if(j < i) {
                a[i] += pow(-1, j) * gain;
            }
            b[i] += (1.0 - 2.0 * i) * cos(j * M_PI / order);
        }
        a[i] *= pow(gain, 2);
        b[i] = pow(b[i], 2) + pow(gain, 2);
    }
}

// 切比雪夫滤波器
void chebyshev_filter(float *x, float *y, int n, float *a, float *b, int order, float rp, float rs, float wp, float ws){
    float w = 2 * M_PI * (ws + wp) / 2.0;
    float s = sin(w);
    float c = cos(w);
    float alpha = s / (2.0 * order);
    float beta = sqrt(pow(rp, 2) - 1.0) / (2.0 * order * s);
    float gamma = pow(beta, 2) + pow(alpha, 2);
    float delta = 2.0 * beta * c;
    float epsilon = pow(c, 2) - pow(alpha, 2);

    // 计算初始条件
    float w0 = 2.0 * M_PI * wp;
    float T = 1.0 / (2.0 * M_PI * wp);
    float a0 = 1.0;
    float a1 = -2.0 * c / (1.0 + T * delta + pow(T, 2) * epsilon);
    float a2 = (pow(T, 2) * pow(c, 2) - 2.0) / (1.0 + T * delta + pow(T, 2) * epsilon);
    float b1 = (2.0 * (1.0 - pow(T, 2) * gamma)) / (1.0 + T * delta + pow(T, 2) * epsilon);
    float b2 = (1.0 - T * delta + pow(T, 2) * epsilon) / (1.0 + T * delta + pow(T, 2) * epsilon);

    // 滤波操作
    for(int i = 0; i < n; i++) {
        y[i] = a0 * x[i] + a1 * x[i-1] + a2 * x[i-2] - b1 * y[i-1] - b2 * y[i-2];
    }
}

这段代码实现了一个4阶的切比雪夫滤波器，可以根据需要修改阶数和其他参数。