Objective-C?????????FFT

????????FFT????????????????DFT??????????FFT???????????????????????Objective-C??FFT???????????

??Objective-C??

????Xcode???????macOS??????Command Line Tool???????????????Objective-C????????FFTObjectiveC??

??FFT??

?main.m?????FFT??????????????????

#import

??????FFT????????????????

int main(int argc, const char *argv) {
    int n = 8; // ?????????8
    int m = 1; // ?????????1
    
    // ????
    int *x = (int *)malloc(n * sizeof(int));
    for (int i = 0; i < n; i++) {
        x[i] = sin(i * M_PI / 180); // ?????????
    }
    
    // FFT??
    // ???FFT?????????
    // ...
    
    // ????
    printf("FFT??!\n");
    
    free(x);
    return 0;
}

??????????????????FFT??????????????????????FFT?????

#include 
   
    
#include 
    
     
#include 
     
      
// ??????
typedef struct {
    int real;
    int imag;
} Complex;
// FFT????
Complex *fft(Complex *input, int n) {
    Complex *output = malloc(sizeof(Complex) * n);
    
    // ???FFT????????
    for (int i = 0; i < n; i++) {
        output[i] = input[i];
    }
    
    return output;
}
int main(int argc, const char *argv) {
    int n = 8; // ??????
    int m = 1; // ??????
    
    // ??????
    Complex *x = malloc(n * sizeof(Complex));
    for (int i = 0; i < n; i++) {
        x[i].real = sin(i * M_PI / 180);
        x[i].imag = 0;
    }
    
    // FFT??
    Complex *y = fft(x, n);
    
    // ??????
    printf("FFT????????%d\n", y[0].real);
    
    free(x);
    free(y);
    return 0;
}

??????????FFT?????FFT????????????????????????????????????FFT????????????????FFT?

FFTW: ??????FFT?????????????

Accelerate??: Apple???Accelerate?????FFT???

Numerix: ??Objective-C??FFT???

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?????????????????????????FFT???????????????? frameworks?

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?????????: ?????????2????

FFT????: ??FFT???????????????FFT?????

????: ???????FFT??????????FFTW?Accelerate???

????

??????????FFT??????

// ????
int n = 8;
Complex *x = malloc(n * sizeof(Complex));
for (int i = 0; i < n; i++) {
    x[i].real = sin(i * M_PI / 180);
    x[i].imag = 0;
}
// FFT??
Complex *y = fft(x, n);
// ?FFT??
Complex *z = fft(y, n);
// ??????
for (int i = 0; i < n; i++) {
    printf("%f\n", z[i].real);
}