$f$ Riemann int; $\exists$ cont. fcn. $g$ s.t $\int |f(x)-g(x)| dx < \epsilon$. Show supp $g$ can be taken to be arbitrarily small nbhd of supp $f$.

49 Views Asked by At

Suppose $f$ is a Riemann integrable function and for $\epsilon>0$, there is a continuous function $g$ so that $\int |f(x)-g(x)| \ dx < \epsilon$. Show that the support of $g$, $\text{supp } g$, can be taken to be an arbitrarily small neighborhood of the support of $f$, $\text{supp }f$.

Since we can make the integral of $|f-g|$ arbitrarily small, wouldn't this mean that the support of $f$ and support of $g$ are similar in size?

How can we have support of $g$ be arbitrarily small inside the support of $f$?