public static SparseMatrix block(Matrix a, Matrix b, Matrix c, Matrix d) {
        return CRSMatrix.block(a, b, c, d);
    }
public static SparseMatrix block ( Matrix a , Matrix b , Matrix c , Matrix d ) { return CRSMatrix . block ( a , b , c , d ) ; }
Creates a block {@link SparseMatrix} of the given blocks {@code a},
{@code b}, {@code c} and {@code d}.