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Given an analytic function $\, f : \mathbb{R} \rightarrow \mathbb{R}$ with no known closed formula for its antiderivative. Assume further that by some clever tricks you managed to calculate the definite integral for a fixed number $c$: $$A := \int_0^c f(t) \,dt \; .$$ Is there a way to calculate $\int_0^c t \, f(t) \, dt$ in terms of $A$, $f$ and $f^{(n)}$?

Integration by parts yields $$\int_0^c t \, f(t) \, dt = cA - \int_0^c \int_0^t \, f(\tau) \, d\tau \,dt \; ,$$ which made it seem plausible to me that such a formula exists.

Related Question:
This problem is an abstraction of my more concrete question asked here.

  • You need to be more explicit about what "calculate $\int_0^c t , f(t) , dt$ in terms of $A$, $f$ and $f'$" means. Your integration-by-parts formula is such a calculation, which uses only $A$ and $f$. Why is this not acceptable? What is it you are after that this does not provide? – Paul Sinclair Jan 05 '19 at 12:02
  • My integration-by-parts formula is not acceptable because the antiderivative of $f$ is not known. Hence, this formula is useless as it cannot be evaluated (at least not in an obvious way). Ultimately I just want to be able to explicitly calculate the integral $\int_{0}^c tf(t)dt$, only knowing $A$ and how to evaluate $f$, $f^{(n)}$. – chickenNinja123 Jan 05 '19 at 12:18

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