wtf.py

# halp?

def foo(x, y):
  return f(x, y) + g(x, y)
g_foo = grad(foo, argnum=1)

bar = a + b
g_bar = tf.gradients(bar, var_list)

# g_bar == g_foo(x, y) ... TRUE

# Now, changing the respective plus signs to minus signs ...

def foo(x, y):
  return f(x, y) - g(x, y)
g_foo = grad(foo, argnum=1)

bar = a - b
g_bar = tf.gradients(bar, var_list)

# g_bar == g_foo(x, y) ... FALSE