### Question:
ColumnVector { public ColumnVector sqrt() { return this.transform(ColumnVector.this.matrix::sqrt); } ColumnVector(final int size);  ColumnVector(final double... vector); private  ColumnVector(final Matrix matrix); int size(); double getAt(final int index); void setAt(final int index, final double val); void incrementAt(final int index, final double val); void normalize(); void scale(final double scale); ColumnVector multiplyElementWise(final ColumnVector vector); ColumnVector addElementWise(final ColumnVector vector); double absSum(); double sum(); ColumnVector roundTo(final int numPlaces); ColumnVector add(final double scalar); ColumnVector multiply(final double scalar); ColumnVector sqrt(); ColumnVector abs(); final boolean isZeroVector(); double[] getRaw(); void setAll(final double val); boolean align(); double max(); double median(); double getMagnitude(); double l1Distance(final ColumnVector vector); double l2Distance(final ColumnVector vector); double correlation(final ColumnVector vector); @Override String toString(); void removeNegatives(); @Override int hashCode(); @Override boolean equals(final Object obj);  }### Answer:
@Test public void vectorCanBeSquareRooted() { final ColumnVector vector = new ColumnVector(625, 36, 121); final ColumnVector result = vector.sqrt(); MatcherAssert.assertThat(result, IsNot.not(IsEqual.equalTo(vector))); MatcherAssert.assertThat(result, IsEqual.equalTo(new ColumnVector(25.0, 6.0, 11.0))); }