package shtick.math;

//////////////////////////////////////////////////////
//**************************************************//
//*               FourierBasis Class               *//
//*                                                *//
//* Version 1.2                                    *//
//* Author: Sean M. Cox                            *//
//* Organization: The Shtick                       *//
//* http://www.smcox.com/                          *//
//*                                                *//
//* Contructs a basis for a sine and cosine space  *//
//* useful for data of a given length provided in  *//
//* to the class in the constructor. This class    *//
//* was created and implemented in order to        *//
//* optimize calculations in arrays of             *//
//* FourierSeries classes translating data sets of *//
//* equal length.                                  *//
//*                                                *//
//**************************************************//
//////////////////////////////////////////////////////

public class FourierBasis{
  private double[][] sineBasis;
  private double[][] cosineBasis;

  public FourierBasis(int dataLength){
    int harmonics=dataLength/2;
    sineBasis=new double[harmonics+1][dataLength];
    cosineBasis=new double[harmonics+1][dataLength];
    for(int j=0;j<dataLength;j++){
      sineBasis[0][j]=1;
      cosineBasis[0][j]=1;
    }
    for(int i=1;i<=harmonics;i++){
      for(int j=0;j<dataLength;j++){
        sineBasis[i][j]=Math.sin(i*2*Math.PI*(j+.5)/sineBasis[0].length);
        cosineBasis[i][j]=Math.cos(i*2*Math.PI*(j+.5)/cosineBasis[0].length);
      }
    }
  }

  public double[][] getSineBasis(){
    return sineBasis;
  }

  public double[][] getCosineBasis(){
    return cosineBasis;
  }
}