def fdiff(self, argindex=1):
        if len(self.args) == 3:
            n, z, m = self.args
            fm, fn = sqrt(1 - m*sin(z)**2), 1 - n*sin(z)**2
            if argindex == 1:
                return (elliptic_e(z, m) + (m - n)*elliptic_f(z, m)/n +
                        (n**2 - m)*elliptic_pi(n, z, m)/n -
                        n*fm*sin(2*z)/(2*fn))/(2*(m - n)*(n - 1))
            elif argindex == 2:
                return 1/(fm*fn)
            elif argindex == 3:
                return (elliptic_e(z, m)/(m - 1) +
                        elliptic_pi(n, z, m) -
                        m*sin(2*z)/(2*(m - 1)*fm))/(2*(n - m))
        else:
            n, m = self.args
            if argindex == 1:
                return (elliptic_e(m) + (m - n)*elliptic_k(m)/n +
                        (n**2 - m)*elliptic_pi(n, m)/n)/(2*(m - n)*(n - 1))
            elif argindex == 2:
                return ((m - 1)/elliptic_e(m) + elliptic_pi(n, m))/(2*(n - m))
        raise ArgumentIndexError(self, argindex)
dataset/ETHPy150Open sympy/sympy/sympy/functions/special/elliptic_integrals.py/elliptic_pi.fdiff/swapped operands of `/`