Code:
//This is a sample program to perform 2D FFT inplace
import java.util.Scanner;
public class TwoD_FFT
{
static void twoDfft(double[][] inputData, double[][] realOut,
double[][] imagOut, double[][] amplitudeOut)
{
int height = inputData.length;
int width = inputData[0].length;
// Two outer loops iterate on output data.
for (int yWave = 0; yWave < height; yWave++)
{
for (int xWave = 0; xWave < width; xWave++)
{
// Two inner loops iterate on input data.
for (int ySpace = 0; ySpace < height; ySpace++)
{
for (int xSpace = 0; xSpace < width; xSpace++)
{
// Compute real, imag, and ampltude.
realOut[yWave][xWave] += (inputData[ySpace][xSpace] * Math
.cos(2
* Math.PI
* ((1.0 * xWave * xSpace / width) + (1.0
* yWave * ySpace / height))))
/ Math.sqrt(width * height);
imagOut[yWave][xWave] -= (inputData[ySpace][xSpace] * Math
.sin(2
* Math.PI
* ((1.0 * xWave * xSpace / width) + (1.0
* yWave * ySpace / height))))
/ Math.sqrt(width * height);
amplitudeOut[yWave][xWave] = Math
.sqrt(realOut[yWave][xWave]
* realOut[yWave][xWave]
+ imagOut[yWave][xWave]
* imagOut[yWave][xWave]);
}
System.out.println(realOut[yWave][xWave] + " + "
+ imagOut[yWave][xWave] + " i");
}
}
}
}
public static void main(String args[])
{
System.out.println("Enter the size: ");
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
double[][] input = new double[n][n];
double[][] real = new double[n][n];
double[][] img = new double[n][n];
double[][] amplitutude = new double[n][n];
System.out.println("Enter the 2D elements ");
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++)
input[i][j] = sc.nextDouble();
twoDfft(input, real, img, amplitutude);
sc.close();
}
}
Output:
Enter the size:
2
Enter the 2D elements
2 3
4 2
2.5 + 0.0 i
5.5 + 0.0 i
-0.5 + -1.8369701987210297E-16 i
0.5 + -3.0616169978683826E-16 i
2.5 + 0.0 i
-0.5 + -3.6739403974420594E-16 i
-0.5 + -1.8369701987210297E-16 i
-1.5 + -1.8369701987210297E-16 i
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