dsp.C Program to compute Discrete Fourier Transform(DFT) of a sequence X(n) of Length N

/* C Program to compute Discrete Fourier Transform(DFT)
   of a sequence X(n) of Length N

   Inputs : 1)Number of samples of x(n) i.e. N
   2)Values of samples of x(n)
   Outputs: N point DFT X(k) with its real and imaginary parts.

   Assumptions: The sequence x(n) is considered real.
===============================================================*/
#include<stdio.h>
#include<conio.h>
#include<math.h>
#include<graphics.h>

void main()
{
 float static X[100],X_Real[100],X_Imag[100];
 float k,n,N;
 clrscr();

 printf("\t\t\t Discrete Fourier Transform(DFT)");
 printf("\n\n Enter the number samples in the sequence X(n),N=");
 scanf("%f",&N);
 printf("\n\n Enter the samples of sequence X(n):");

 for(n=0;n<N;n++)
 {
  printf("X(%d)=",n);
  scanf("%f",&X[n]);
 }

 for(k=0;k<N;k++)
 {
  X_Real[k]=X_Imag[k]=0.0;

  for(n=0;n<N;k++)
  {
   X_Real[k]=X_Real[k]+X[n]*cos((2*M_PI*k*n)/N);
   X_Imag[k]=X_Imag[k]+X[n]*sin((2*M_PI*k*n)/N);
  }
  X_Imag[k]=X_Imag[k]*(-1.0);
 }

 printf("\n The %d  point DFT of given sequence is..",N);
 printf("\n\t Real X(k)\t\t Imaginary X(k)");
 for(k=0;k<N;k++)
  printf("\n X(%d)=%f\t\t %f",k,X_Real[k],X_Imag[k]);
 getch();
}



op*******


               

             Discrete Fourier Transform(DFT)


 Enter the number samples in the sequense X(n)=4

 Enter the samples of sequence X(n):

 X(0)=1

 X(1)=2

 X(2)=0

 X(3)=1

 The 4 point DFT of given sequence is:

       Real X[k]               Imaginary X[k]

     X(0)=4.000000             -0.000000
     X(1)=1.000000             -1.000000
     X(2)=-2.000000            -0.000000
     X(3)=1.000000              1.000000