Performs a symmetric rank-1 update operation:
    A <- A + alpha * np.dot(x,x.T)

    :param A: Symmetric NxN np.array
    :param x: Nx1 np.array
    :param alpha: scalar

def DSYR_blas(A, x, alpha=1.):
    """
    Performs a symmetric rank-1 update operation:
    A <- A + alpha * np.dot(x,x.T)

    :param A: Symmetric NxN np.array
    :param x: Nx1 np.array
    :param alpha: scalar

    """
    At = blas.dsyr(lower=0, x=x, a=A, alpha=alpha, overwrite_a=False) #See https://github.com/scipy/scipy/issues/8155
    A[:] = At
    symmetrify(A, upper=True)