@Test
public void testSprSparseDense1() {

    double alpha = 3.0;
    SparseVector v = sparseFromArray(new double[] {1.0, 2.0});
    DenseVector u = new DenseVector(new double[] {3.0, 13.0, 20.0, 0.0});
    DenseMatrix a = new DenseMatrix(new double[][] {{3.0, 0.0}, {13.0, 20.0}},
        StorageConstants.COLUMN_STORAGE_MODE);
    DenseMatrix exp = (DenseMatrix)new DenseMatrix(new double[][] {
        {1.0, 0.0},
        {2.0, 4.0}}, StorageConstants.COLUMN_STORAGE_MODE).times(alpha).plus(a);
    //m := alpha * v * v.t + A
    Blas.spr(alpha, v, u);
    DenseMatrix mu = fromVector(u, a.rowSize(), StorageConstants.COLUMN_STORAGE_MODE, (i, j) -> i >= j);
    Assert.assertEquals(exp, mu);
}