code: public void setComplex(int x, int y, double real, double imag){
  		int idx=y*width+x;
  		setComplex_atIndex(idx, real, imag);
  	}
docs: Sets the real and imaginary part at the specified position
  <br>
  If {@link #isSynchronizePowerSpectrum()} is true, then this will also
  update the corresponding power value.
  @param x coordinate
  @param y coordinate
  @param real part to be set
  @param imag imaginary part to be set