@Test
public void linear() {

  DoubleColumn col =
      DoubleColumn.create(
              "testCol", new double[] {missing, 1.0, missing, missing, missing, 5.0, missing})
          .interpolate()
          .linear();
  assertArrayEquals(
      new double[] {missing, 1.0, 2.0, 3.0, 4.0, 5.0, missing}, col.asDoubleArray());
}