import streamit.*;
import streamit.io.*;

class chold extends Filter // this Filter performs the cholesky decomposition through 
   {
    int    N; //  the dimension of AhA
    float[][]  A; // A is the input matrix 
    
    float[]  p; // p is the out put elements on the diagonal
    float    sum; // sum will be used as a buffer         
public chold(int N){ super (N);}
          public void init (int N) {
	      input = new Channel(Float.TYPE, N*(N+1)/2);
	      output = new Channel(Float.TYPE, N*(N+1)/2);
          A= new float[N][N];
          p=new float[N];
	  this.N=N;
             
          } 
 

public void work() {
    float sum; // sum serves as a buffer
  for (int i=0; i<N;i++)
      {  
      for (int j=0; j<=i ; j++)
      A[i][j]=input.popFloat(); 

      }
  
  for (int i=0; i <N ; i++) { 
      for (int j=i; j<N ; j++) {
	  sum=A[j][i];
	  for (int k=i-1 ; k>=0; k--) sum-=A[k][i]*A[k][j];
      if ( i==j)
	  {
	      p[i]=(float)Math.sqrt(sum);
	      output.pushFloat(p[i]);
	      }
      else
	  {
	      A[i][j]=sum/p[i];
	      output.pushFloat(A[i][j]);
          }
      } }
	     
}


}