# how did u calculate this integral

• Nov 18th 2009, 04:23 PM
pengchao1024
how did u calculate this integral
wait. my question has been changed:

Use the Riemann-Lebesgue Lemma to get the asymptotic expansion of :

$I(m)=\int_{a}^{\infty}{f(t)cos(mt)dt} \ \ \ \ as \ \ \ \ m\rightarrow\infty$
• Nov 18th 2009, 04:26 PM
mr fantastic
Quote:

Originally Posted by pengchao1024
$\int_{-\infty}^{\infty}{e^{-x\sqrt{3} r^{2}}dr} \ \ \ \ \ \ \ \ as \ \ \ \ r\rightarrow\infty$

Is it meant to be $\int_{-\infty}^{\infty}{e^{-x\sqrt{3} r^{2}}d{\color{red}x}} \ \ \ \ \ \ \ \ as \ \ \ \ r\rightarrow\infty$ ?