a(x,t)

amax = sin(t / 4.5 - x[0] / 2);
    for (i = 1; i < Nx + 1; i++)
    {
        a = sin(t / 4.5 - x[i] / 2);
        if (abs(a) > amax)
            amax = abs(a);
    }
    if (amax != 0)
        Ht = Hx / amax;
    else
        Ht = Hx;
    Uj1[0] = Mu(t);
    for (i = 0; i < Nx + 1; i++)
    {
        a = sin(t / 4.5 - x[i] / 2);
        aaa << a << "\n";
        gm = a * Ht / Hx;
        nn = 1;
        if (i == 0)
            nn = 0;
        if (i == Nx + 1)
            nn = 2;
        switch (nn)
        {
        case 0:
            if (gm < 0)
                Uj1[i] = (1 + gm) * Uj[i] - gm * Uj[i + 1];
            break;
        case 1:
            if (gm >= 0)
                Uj1[i] = (1 - gm) * Uj[i] + gm * Uj[i - 1];
            else
                Uj1[i] = (1 + gm) * Uj[i] - gm * Uj[i + 1];
            break;
        case 2:
            if (gm > 0)
                Uj1[i] = (1 - gm) * Uj[i] + gm * Uj[i - 1];
            else
                Uj1[i] = Uj[i];
            break;
        }
    }