//-------------------------------------------------------------------------
public virtual void test_diagonal()
{
assertMatrix(DoubleMatrix.diagonal(DoubleArray.EMPTY));
assertMatrix(DoubleMatrix.diagonal(DoubleArray.of(2d, 3d, 4d)), 2d, 0d, 0d, 0d, 3d, 0d, 0d, 0d, 4d);
assertEquals(DoubleMatrix.diagonal(DoubleArray.of(1d, 1d, 1d)), DoubleMatrix.identity(3));
}