MATLAB函数fir1的C语言移值

要移值的matlab函数：

h3 = fir1(16,[0.25 0.50]);

C语言版本

#include <iostream>
#include <cmath>

#define PI acos(-1)

double sincEasy(double *x, int len, int index) {
	double temp = PI * x[index];
	if (temp == 0) {
		return 1.0;  // sinc(0) = 1
	}
	return sin(temp) / temp;
}

double* fir1(int lbflen, double Wn[], double lbf[]) {
	double alpha = 0.5 * (lbflen - 1);
	double *m = new double[lbflen];
	double *R_sin = new double[lbflen];
	double *L_sin = new double[lbflen];

	for (int i = 0; i < lbflen; i++) {
		m[i] = i - alpha;
		lbf[i] = 0.0;
	}

	for (int i = 0; i < 2; i += 2) {
		double left = Wn[i];
		double right = Wn[i + 1];
		for (int j = 0; j < lbflen; j++) {
			R_sin[j] = right * m[j];
			L_sin[j] = left * m[j];
			lbf[j] += right * sincEasy(R_sin, lbflen, j) - left * sincEasy(L_sin, lbflen, j);
		}
	}

	// Apply window function
	for (int i = 0; i < lbflen; i++) {
		double Win = 0.54 - 0.46 * cos(2.0 * PI * i / (lbflen - 1));
		lbf[i] *= Win;
	}

	// Scaling, if needed
	double scale_frequency = 0.5 * (Wn[0] + Wn[1]);
	double s = 0.0;
	for (int i = 0; i < lbflen; i++) {
		s += lbf[i] * cos(PI * m[i] * scale_frequency);
	}
	for (int i = 0; i < lbflen; i++) {
		lbf[i] /= s;
	}

	delete[] m;
	delete[] R_sin;
	delete[] L_sin;
	return lbf;
}

int main() {
	int lbn = 16;
	double Wn[2] = { 0.25, 0.50 };
	double* lbf = new double[lbn + 1];

	lbf = fir1(lbn + 1, Wn, lbf);

	// Output coefficients for verification
	for (int i = 0; i < lbn + 1; i++) {
		std::cout << lbf[i] << " ";
	}
	std::cout << std::endl;

	delete[] lbf;
	system("pause");
	return 0;
}

结果是完全一样的，OK！