I am sure most of you are familiar with what is known as Feynman integration.
For those who are not, it allows us to integrate otherwise difficult integrals. Ones we would use
contour integration on. We choose a parameter. A 'suitable dominating
function' which we can use to make the integrand friendlier.
Example:
Let's integrate
With this one it is not immediately seen where we can use our parameter.
But, if we rewrite it as follows:
, we can do this:
Integrate w.r.t a gives us:
Now, leaving a=1, we get:
Which, by the way, gives the result of another famous one:
I know, this is Leibniz. But it is a cool way to integrate. the trick is finding the parameter.
It works pretty slick on:
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How about trying it on the famous Fresnel integrals:
or
by choosing the proper parameter.