Commit 2024-04-05 23:03 9db18cff
View on Github →feat: integration by parts on the whole real line, assuming integrability of the product (#11916)
We already have that ∫ (x : ℝ), u x * v' x = b' - a' - ∫ (x : ℝ), u' x * v x
if u * v
tends to a'
and b'
at minus infinity and infinity. Assuming morevoer that u * v
is integrable, we show that it tends to 0
at minus infinity and infinity, and therefore that ∫ (x : ℝ), u x * v' x = - ∫ (x : ℝ), u' x * v x
. We also give versions with a general bilinear form instead of multiplication.