C 语言 fft 1024代码

以下是一个简单的 C 语言 FFT 1024 的代码示例：

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

#define PI 3.14159265359

void fft(double *real, double *imag, int n) {
    int i, j, k, m;
    double arg, cosarg, sinarg;
    double *real_tmp, *imag_tmp;

    // Allocate memory for temporary arrays
    real_tmp = (double*)malloc(n * sizeof(double));
    imag_tmp = (double*)malloc(n * sizeof(double));

    // Copy input data to temporary arrays
    for (i = 0; i < n; i++) {
        real_tmp[i] = real[i];
        imag_tmp[i] = imag[i];
    }

    // Calculate FFT
    m = log2(n);
    for (i = 0; i < m; i++) {
        k = 1 << i;
        for (j = 0; j < k; j++) {
            arg = -2 * j * PI / (2 * k);
            cosarg = cos(arg);
            sinarg = sin(arg);
            for (int l = j; l < n; l += 2 * k) {
                double t1 = cosarg * real_tmp[l + k] - sinarg * imag_tmp[l + k];
                double t2 = sinarg * real_tmp[l + k] + cosarg * imag_tmp[l + k];
                real_tmp[l + k] = real_tmp[l] - t1;
                imag_tmp[l + k] = imag_tmp[l] - t2;
                real_tmp[l] += t1;
                imag_tmp[l] += t2;
            }
        }
    }

    // Copy data back to real and imag arrays
    for (i = 0; i < n; i++) {
        real[i] = real_tmp[i];
        imag[i] = imag_tmp[i];
    }

    // Free temporary arrays
    free(real_tmp);
    free(imag_tmp);
}

int main() {
    int n = 1024;
    double *real = (double*)malloc(n * sizeof(double));
    double *imag = (double*)malloc(n * sizeof(double));

    // Initialize input data
    for (int i = 0; i < n; i++) {
        real[i] = sin(2 * PI * i / n);
        imag[i] = 0;
    }

    // Perform FFT
    fft(real, imag, n);

    // Print output data
    for (int i = 0; i < n; i++) {
        printf("%lf + %lfi\n", real[i], imag[i]);
    }

    // Free memory
    free(real);
    free(imag);
    return 0;
}

注意：此代码仅供参考，实际使用中需要根据具体情况进行修改和优化。