fdiff | OpenType table diff tool for fonts

>>> from sympy.abc import x
>>> f = x**2
>>> df = 2*x

In [10]: class myf(Function):
    ...:     def fdiff(self, i):
    ...:         assert i == 1
    ...:         return 2*x
    ...:   

>>> sqrt(x/y)
sqrt(x/y)
>>> sqrt(x/3)
sqrt(3)*sqrt(x)/3

>>> print(sympy.simplify(sympy.diff(G(x), x))).subs(pi, 3)
H(1/sqrt(x))

>>> S.Pi.n(3)
3.14

expm1 = lambda x: exp(x)-1
parse_expr('expm1(x)', local_dict={"expm1": expm1})

class expm1(Function):
    def fdiff(self, argindex=1):
        return exp(self.args[0])

e = parse_expr('expm1

In [71]: arr = np.random.randint(-5,5,10)
In [72]: arr
Out[72]: array([ 3,  4,  2, -3, -1,  0, -5,  4,  2, -3])
In [73]: arr.shape
Out[73]: (10,)
In [74]: np.where(arr>=0)
Out[74]: (array([0, 1, 2, 5, 7, 8]),)
In [75]: arr[_]
Out[75]: a

class f(Function):
  def fdiff(self, argindex):
    if argindex == 1:
      return f(self.args[0], self.args[1] + 1)
    else:
      raise ArgumentIndexError(self, argindex)

f(x, y + 3) + Subs(Derivative(f(x, _xi_2