docs: public static double[] mergeCoords(double[] x, double[] y) {
          if (x.length != y.length)
              throw new IllegalArgumentException(
                              "Sample sizes must be the same for each data applyTransformToDestination.");
          double[] ret = new double[x.length + y.length];
  
          for (int i = 0; i < x.length; i++) {
              ret[i] = x[i];
              ret[i + 1] = y[i];
          }
          return ret;
      }