### Question:
Matrix { public final void scale(final double scale) { this.forEach((row, col, value, setter) -> setter.accept(value / scale)); } protected  Matrix(final int numRows, final int numCols); final int getElementCount(); final int getRowCount(); final int getColumnCount(); final double getAt(final int row, final int col); final void setAt(final int row, final int col, final double val); final void incrementAt(final int row, final int col, final double val); final ColumnVector getRowSumVector(); final ColumnVector getColumnSumVector(); Collection<Integer> normalizeColumns(); void removeNegatives(); void removeLessThan(final double minValue); final void scale(final double scale); Matrix multiplyElementWise(final Matrix matrix); Matrix addElementWise(final Matrix matrix); final double absSum(); final double sum(); ColumnVector multiply(final ColumnVector vector); final Matrix transpose(); Matrix roundTo(final int numPlaces); Matrix multiply(final double scalar); Matrix add(final double scalar); Matrix abs(); Matrix sqrt(); final boolean isSameSize(final Matrix matrix); final boolean isZeroMatrix(); @Override int hashCode(); @Override boolean equals(final Object obj); void forEach(final ReadOnlyElementVisitorFunction func); abstract MatrixNonZeroElementRowIterator getNonZeroElementRowIterator(final int row);  }### Answer:
@Test public void denseMatrixCanBeScaled() { final Matrix matrix = this.createMatrix(3, 2, new double[] {2, 3, 5, 11, 1, 8}); matrix.scale(10); MatcherAssert.assertThat( matrix, IsEqual.equalTo(this.createMatrix(3, 2, new double[] {0.2, 0.3, 0.5, 1.1, 0.1, 0.8}))); }