. Minimal case is
sage: f=function("f")
sage: F(x)=integrate(f(t),t,0,x)
sage: diff(F(x),x)
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-87-d4bc7769bfb7> in <module>()
----> 1 diff(F(x),x)
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/calculus/functional.py in derivative(f, *args, **kwds)
134 if not isinstance(f, Expression):
135 f = SR(f)
--> 136 return f.derivative(*args, **kwds)
137
138 diff = derivative
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression.derivative (build/cythonized/sage/symbolic/expression.cpp:25543)()
4172 ValueError: No differentiation variable specified.
4173 """
-> 4174 return multi_derivative(self, args)
4175
4176 diff = differentiate = derivative
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/misc/derivative.pyx in sage.misc.derivative.multi_derivative (build/cythonized/sage/misc/derivative.c:3118)()
220
221 for arg in derivative_parse(args):
--> 222 F = F._derivative(arg)
223 return F
224
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression._derivative (build/cythonized/sage/symbolic/expression.cpp:26060)()
4244 sig_on()
4245 try:
-> 4246 x = self._gobj.diff(ex_to_symbol(symbol._gobj), deg)
4247 finally:
4248 sig_off()
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/symbolic/integration/integral.py in _tderivative_(self, f, x, a, b, diff_param)
254 ans = SR.zero()
255 return (ans + f.subs(x == b) * b.diff(diff_param)
--> 256 - f.subs(x == a) * a.diff(diff_param))
257
258 def _print_latex_(self, f, x, a, b):
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/structure/element.pyx in sage.structure.element.Element.__getattr__ (build/cythonized/sage/structure/element.c:4608)()
487 AttributeError: 'LeftZeroSemigroup_with_category.element_class' object has no attribute 'blah_blah'
488 """
--> 489 return self.getattr_from_category(name)
490
491 cdef getattr_from_category(self, name):
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/structure/element.pyx in sage.structure.element.Element.getattr_from_category (build/cythonized/sage/structure/element.c:4717)()
500 else:
501 cls = P._abstract_element_class
--> 502 return getattr_from_other_class(self, cls, name)
503
504 def __dir__(self):
/usr/local/sage-P3-2/local/lib/python3.7/site-packages/sage/cpython/getattr.pyx in sage.cpython.getattr.getattr_from_other_class (build/cythonized/sage/cpython/getattr.c:2614)()
392 dummy_error_message.cls = type(self)
--> 394 raise AttributeError(dummy_error_message)
395 attribute = <object>attr
396 # Check for a descriptor (__get__ in Python)
AttributeError: 'sage.rings.rational.Rational' object has no attribute 'diff'
I donot understand this error, and I expected to see sometning along the lines of f(x)...