def inner(s, z): return phi(z) * (Phi(z + q * s) - Phi(z))**(k - 1)
def integral(q, s, z): return k * (k - 1) * s * phi(z) * phi(s * q + z) \ * (Phi(s * q + z) - Phi(z)) ** (k - 2)
def integrand(z): return phi(z) * (Phi(z + q) - Phi(z))**(k - 1)
def inner(q, s, z): return phi(z + q * s) * phi(z) * (Phi(z + q * s) - Phi(z)) ** (k - 2)