docs: public void setInput(float x[], float y[], int size) {
  		if (x.length < size || y.length < size) {
  			throw new IllegalArgumentException("Arrays too small for size.");
  		}
  		if (size < M) {
  			throw new IllegalArgumentException("Not enough data points for M");
  		}
  
  		this.x = x;
  		this.y = y;
  		this.size = size;
  		this.dj = Math.min(1, (int) Math.pow(size, 0.25));
  		ascend = x[size - 1] >= x[0];
  	}