English
The torus integral is linear: torusIntegral(f,c,R) + torusIntegral(g,c,R) = torusIntegral(f+g,c,R).
Русский
Торо-интеграл линейен: сумма интегралов равна интегралу суммы.
LaTeX
$$$\operatorname{torusIntegral}(f,c,R) + \operatorname{torusIntegral}(g,c,R) = \operatorname{torusIntegral}(f+g,c,R)$$$
Lean4
theorem torusIntegral_add (hf : TorusIntegrable f c R) (hg : TorusIntegrable g c R) :
(∯ x in T(c, R), f x + g x) = (∯ x in T(c, R), f x) + ∯ x in T(c, R), g x := by
simpa only [torusIntegral, smul_add, Pi.add_apply] using integral_add hf.function_integrable hg.function_integrable