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/*
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This is the java implementation of calculating coefficients of the given function performing the Discrete-Fourier Transform. Formula for calculating the coefficient is X(k) = Sum(x(n)*cos(2*PI*k*n/N) – iSum(x(n)*sin(2*PI*k*n/N)) over 0 to N-1
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*/
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//This is a sample program to calculate a DFT Coefficients using the formula
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import java.util.Scanner;
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public class DFT_Coefficient
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{
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double real, img;
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public DFT_Coefficient()
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{
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this.real = 0.0;
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this.img = 0.0;
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}
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public static void main(String args[])
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{
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int N = 10;
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Scanner sc = new Scanner(System.in);
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System.out.println("Calculation DFT Coefficients");
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System.out.println("Enter the coefficient of simple linear funtion:");
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System.out.println("ax + by = c");
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double a = sc.nextDouble();
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double b = sc.nextDouble();
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double c = sc.nextDouble();
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double []function = new double[N];
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for(int i=0; i<N; i++)
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{
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function[i] = (((a*(double)i) + (b*(double)i)) - c);
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//System.out.print( " "+function[i] + " ");
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}
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System.out.println("Enter the max K value: ");
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int k = sc.nextInt();
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double []cos = new double[N];
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double []sin = new double[N];
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for(int i=0; i<N; i++)
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{
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cos[i] = Math.cos((2 * i * k * Math.PI) / N);
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sin[i] = Math.sin((2 * i * k * Math.PI) / N);
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}
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DFT_Coefficient dft_val = new DFT_Coefficient();
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System.out.println("The coefficients are: ");
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for(int i=0; i<N; i++)
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{
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dft_val.real += function[i] * cos[i];
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dft_val.img += function[i] * sin[i];
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}
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System.out.println("("+dft_val.real + ") - " + "("+dft_val.img + " i)");
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sc.close();
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}
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}
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/*
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Calculation DFT Coefficients
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Enter the coefficient of simple linear funtion:
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ax + by = c
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1 2 3
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Enter the max K value:
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2
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The coefficients are:
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(-15.00000000000001) - (-20.6457288070676 i)
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