Let $\{f_k\}$ be a sequence of functions. Given:
- $f_k$ is a bounded variation function on $[a,b]$ for any $k$
- sequence $f_k$ converges to $f$ point-wise.
Question: is $f$ necessarily a bounded variation function on $[a,b]$?
Let $\{f_k\}$ be a sequence of functions. Given:
Question: is $f$ necessarily a bounded variation function on $[a,b]$?
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Let $a=0,b=1$, $f_n(0)=0$, $f_n(x)=\frac 1 x$ for $x > \frac 1 n$, $n$ for $0<x \leq \frac 1 n$. Let $f(x)=\frac 1 x$ for $x>0$ and $0$ for $x=0$. Then $f$ is not even bounded so it is not of bounded variation. Each $f_n$ is of bounded variation because it is decresing and bounded on $(0,1]$.