DFT JAVA

public class DFT {

public  static void calc(float[] zaihe) {

int npt = 200;

float[] XR = new float[npt];

float[] XI = new float[npt];

float[] YR = new float[npt];

float[] YI = new float[npt];

float WN = (float) (-2 * 3.1415926 / npt);

int N = 45;

for (int k = 0; k < npt; k++) {

XR[k] = 0;

XI[k] = 0;

float wk = k * WN;

for (int n = 0; n < npt; n++) {

float c = (float) Math.cos(n * wk);

float s = (float) Math.sin(n * wk);

XR[k] = XR[k] + zaihe[n] * c;

XI[k] = XI[k] + zaihe[n] * s;

}

}

for(int i = N;i<npt-10;i++) {

XR[i] = 0;

XI[i] = 0;

}

for (int k = 0; k < npt; k++) {

YR[k] = 0;

YI[k] = 0;

float wk = - k * WN;

 

for (int n = 0; n < npt; n++) {

float c = (float) Math.cos(n * wk);

float s = (float) Math.sin(n * wk);

YR[k] = YR[k] + XR[n] * c + XI[n]*s;

YI[k] = YI[k] + XR[n] * s + XI[n]*c;

}

}

 

for(int i = 0;i<npt;i++) {

zaihe[i] = (float) Math.pow(Math.pow(YR[i],2) + Math.pow(YI[i], 2),0.5);

zaihe[i]/=npt;

System.out.println(zaihe[i]);

}

}

}