docs: public void removeKnot(int n) {
  		if (numKnots <= 4)
  			return;
  		if (n < numKnots-1) {
  			System.arraycopy(xKnots, n+1, xKnots, n, numKnots-n-1);
  			System.arraycopy(yKnots, n+1, yKnots, n, numKnots-n-1);
  			System.arraycopy(knotTypes, n+1, knotTypes, n, numKnots-n-1);
  		}
  		numKnots--;
  		if (xKnots[1] > 0)
  			xKnots[1] = 0;
  		rebuildGradient();
  	}